Abstract:
The present inventors used the previously developed H77/JFH1 T27OOC,A4O8OT  (1a/2a), J4/JFH 1T2996C,A4827T,ΔHVRI  (1b/2a), J6/JFH 1ΔHVRI  (2a/2a), J8/JFH1 ΔHVRI  (2b/2a), S52/JFH1 T27i8G,τ7i6oc  (3a/2a), SA13/JFH1 C34O5G,A3696G  (5a/2a) and HK6a/JFH1T 1389c,A1590G  (6a/2a) constructs for the deletion of Hypervariable Region 1 (HVR1) to construct viable, JFH1 (geno-type 2a) based, genomes. The present inventors serially passaged the viruses in cell culture obtaining relatively high HCV RNA titers and infectivity titers. Sequence analysis of the viruses identified mutations adapting H77/JFH1 T27OOC,A4O8OT,ΔHVR1  (1a/2a), J8/JFH 1ΔHVR1  (2b/2a), S52/JFH1 T2718G,T716OC,ΔHVR1  (3a/2a) and J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a) to the HVR1 deletion.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    This invention provides infectious recombinant hepatitis C viruses (HCV) lacking the Hypervariable Region 1 (HVR1), and vectors, cells and animals comprising the same. The present invention provides methods of producing the infectious recombinant HCV lacking HVR1, and their use in identifying anti-HCV therapeutics including use in development of vaccines and diagnostics, as well as sequences of HCV associated with HCV pathogenesis. 
       BACKGROUND OF THE INVENTION 
       [0002]    Hepatitis C virus (HCV) is one of the most widespread infectious diseases in the world. About 170 million people are infected with HCV worldwide with a yearly incidence of 3-4 million. While the acute phase of infection is mostly asymptomatic, the majority of acutely infected individuals develop chronic hepatitis and is at increased risk of developing liver cirrhosis and hepatocellular carcinoma. Thus, HCV infection is a major contributor to end-stage liver disease and in developed countries to liver transplantation. 
         [0003]    HCV is a small, enveloped virus classified as a member of the Flaviviridae family. Its genome consists of a 9.6 kb single stranded RNA of positive polarity composed of 5′ and 3′ untranslated regions (UTRs) and one long open reading frame (ORF) encoding a polyprotein, which is co- and posttranslationally cleaved and thus yields the structural (Core, E1, E2), p7 and nonstructural (NS2, NS3, NS4A, NS4B, NS5A, NS5B) proteins. 
         [0004]    HCV isolates from around the world exhibit significant genetic heterogeneity. At least 7 major HCV genotypes (genotypes 1-7) have been identified, which differ by 31-33% at the nucleotide level. In addition, there are numerous subtypes (a, b, c, etc.). 
         [0005]    Since its discovery in 1989, research on HCV has been hampered by the lack of appropriate cell culture systems allowing for research on the complete viral life cycle as well as new therapeutics and vaccines. 
         [0006]    In 2001, a genotype 2a isolate (JFH1) was described (Kato et al., 2001), which yielded high RNA titers in the replicon system without adaptive mutations (Kato et al., 2003). 
         [0007]    A major breakthrough occurred in 2005, when formation of infectious viral particles was reported after transfection of RNA transcripts from the JFH1 full-length consensus cDNA clone into Huh7 cells (Wakita et al., 2005) (Zhong et al., 2005). 
         [0008]    At the same time, Lindenbach et al. demonstrated that the intragenotypic 2a/2a recombinant genome (J6/JFH1), in which the structural genes (C, E1, E2), p7 and NS2 of JFH1 were replaced by the respective genes of clone J6CF, produced infectious viral particles in Huh7.5 cells (a cell line derived from bulk Huh7 cells) with an accelerated kinetic (Lindenbach et al., 2005). Cell culture derived J6/JFH viruses were apparently fully viable in vivo. Recently the inventors of the present invention developed robust JFH1-based cell culture systems with genotype specific C-NS2 for HCV genotype 1a, 1b, 2b, 3a, 4a, 5a, 6a and 7a. 
         [0009]    A part of the structural gene E2, which is present in all of these genotypes, is the Hypervariable Region 1 (HVR1). HVR1 is generally defined as the N-terminal 26-27 amino acids (aa) of the HCV protein E2 and is marked by the highest variability in the entire HCV genome—even higher than that of the other two HCV hypervariable regions: HVR2 and HVR3. 
         [0010]    The region is easy to recognize in spite of the high variability due to several conserved residues within the sequence. It has previously been demonstrated that specific targeting of HVR1 by the adaptive immune system of the host likely causes the high variability of HVR1 (Manzin et al. 2000 and Ray et al. 1999). 
         [0011]    The inferred immunogenic properties of HVR1, together with the fact that HVR1 specific antibodies are persistently found in patients chronically infected with HCV (Cerino et al. 1997), suggests that an HVR1 specific immune response occurs during an HCV infection, but does not in itself allow clearance of the viral infection. 
         [0012]    It has been suggested that HVR1 acts as an immunological decoy by drawing the attention of the immune system away from less immunogenic, but ultimately more effective epitopes outside of HVR1 (Mondelli et al. 2001). This hypothesis is based on the assumption that HVR1 is not crucial for virus-host interactions since it is difficult to imagine how immune responses targeting HVR1 would not interfere with such interactions. 
         [0013]    Thus, the proposed interaction of HVR1 with the HCV receptor Scavenger Receptor class B type I (SR-BI) (Scarselli et al. 2002) made the “immunological decoy” hypothesis less likely. 
         [0014]    Steinmann et al. have used the HCV intragenotypic recombinant virus, Jc1 (2a/2a) showing that in this specific case HVR1 deletion was tolerated (Steinmann et al., 2007). Like the J6/JFH (2a/2a) virus used by the inventors the Jc1 (2a/2a) virus consists of J6 and JFH1 sequence that has been spliced, but the genotype-junction is at a different location in the HCV genome. As will be shown in the detailed description, viability of HVR1 deleted virus depends greatly on the virus isolates and as such the outcome of HVR1 deletion from J6/JFH could not have been predicted by these earlier observations. 
       SUMMARY OF THE INVENTION 
       [0015]    In the present application the inventors used the previously developed H77/JFH1 T2700C,A4080T  (1a/2a), J4/JFH1 T2996C,A4827T  (1b/2a), J6/JFH1 (2a/2a), J8/JFH1 (2b/2a), S52/JFH1 T2718G,T7160C  (3a/2a), ED43/JFH1 A2819G,A3269T  (4a/2a), SA13/JFH1 C3405G,A3696G  (5a/2a) and HK6a/JFH1 T1389C,A1590G  (6a/2a) constructs for the deletion of Hypervariable Region 1 (HVR1). After HVR1 deletion, in transfection experiments, viral spread was achieved for recombinants: H77/JFH1 T2700C,A4080T  (1a/2a), J4/JFH1 T2996C,A4827T  (1b/2a), J6/JFH1 (2a/2a), J8/JFH1 (2b/2a), S52/JFH1 T2718G,T7160C  (3a/2a), SA13JFH1 C3405G,A3696G  (5a/2a) and HK6a/JFH1 T1389C,A1590G  (6a/2a). 
         [0016]    The present inventors serially passaged the H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J6/JFH1 ΔHVR1  (2a/2a), J8/JFH1 ΔHVR1  (2b/2a), S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a) and HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) virus in cell culture, obtained high HCV RNA titers and infectivity titers and identified and tested additional mutations adapting H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J8/JFH1 ΔHVR1  (2b/2a) and S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a) to the HVR1 deletion. The present inventors also identified a number of other mutations in the envelope proteins for H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a) and J8/JFH1 ΔHVR1  (2b/2a) that are likely candidates to have a similar adapting effect. 
         [0017]    For several JFH1-based recombinants of the different HCV genotypes, several adaptive mutations or combinations thereof were found to confer efficient growth kinetics in cell culture. It is likely, that recombinants containing such adaptive mutations, different from the ones described above, would also be viable after deletion of HVR1. 
         [0018]    These HVR1 deleted viruses potentially allow for developing strategies for raising non-HVR1 based immune responses in patients as well as raising and testing antibodies against non-HVR1 epitopes. Thus, HVR1 deleted viruses may be used as antigens in inactivated virus vaccines. These vaccine development efforts could be targeted at both a prophylactic vaccine, which may be used for immunization of the general population in high prevalence-/incidence countries and for individuals at risk (medical staff, intravenous drug users) in lower prevalence-/incidence countries as well as a therapeutic vaccine, which may be used in HCV infected individuals. 
         [0019]    In addition, HVR1 deleted viruses may be used for raising neutralizing antibodies in laboratory animals, which could later be humanized for use in immunotherapy. These neutralizing antibodies mainly find use as post-exposure prophylaxis e.g. after needle-stick injuries in the medical sector and in conjunction with liver transplantation of individuals with HCV induced end-stage liver disease. 
         [0020]    Cell culture systems employing HVR1 deleted viruses may also be used directly to screen these antibodies for neutralizing effect across genotypes. The use of the HVR1 deleted viruses in conjunction with the parental virus (otherwise identical non-HVR1 deleted construct) would allow the determination of whether HVR1 has any relevance for the neutralizing effect of the given antibody. This use of HVR1 deleted viruses in conjunction with the parental viruses could also be used as a prognostic tool in infected patients by making it possible to assess how much of a patients antibody response is directed against HVR1 and may thus contribute to individualized patient treatment. 
         [0021]    Finally the invention is useful for basic research on the importance and function of HVR1. Thus the developed systems can be used for studies on virus-host interactions including interaction with host receptors. Such studies could help define the HCV protein region of interaction with the host, and thus potentially aid in development of entry inhibitors. 
         [0022]    Thus, one aspect of the invention relates to a replicating RNA comprising the structural gene E2 from human hepatitis C virus, wherein said the structural gene E2 comprises a deletion of at least part of HVR1. 
         [0023]    In another aspect the present invention relates to a composition comprising a nucleic acid molecule according to the present invention, a cassette vector for cloning viral genomes, methods for producing a cell which replicates strain H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J6/JFH1 ΔHVR1  (2a/2a), J8/JFH1 ΔHVR1  (2b/2a), S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), SA13/JFH1 C3405G,A3696G,AHVR1  (5a/2a), HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) or QC69/JFH1 ΔHVR1  (7a/2a) RNA and cells obtainable there from. 
         [0024]    In a further aspect the present invention relates to methods for producing a hepatitis C virus particle and methods for in vitro producing a hepatitis C virus infected cell. 
         [0025]    In a last aspect the present invention relates to methods for screening an anti-hepatitis C virus substance, hepatitis C vaccines comprising a hepatitis C virus particle, methods for producing a hepatitis C virus vaccine and antibodies against hepatitis C virus. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0026]      FIG. 1  shows transfection of J6/JFH with and without HVR1. 
           [0027]      FIG. 2  shows growth kinetics of J6/JFH with and without HVR1 after inoculation with different MOI (multiplicity of infection). 
           [0028]      FIG. 3  shows transfection of J6/JFH ΔHVR1  (corresponding to deletion of aa 384-410) compared to J6/JFH Δ384-411,  J6/JFH Δ384-412 , J6/JFH Δ384-413  and J6/JFH Δ384-414 . 
           [0029]      FIG. 4  shows transfection of H77/JFH1 T2700C,A4080T,ΔHVR1 . 
           [0030]      FIG. 5  shows transfection testing efficacy of adaptive mutations identified for H77/JFH1 T2700C,A4080T,ΔHVR1 . 
           [0031]      FIG. 6  shows transfection of J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a). 
           [0032]      FIG. 7  shows transfection to test efficacy of adaptive mutation T1574A on J8/JFH1 ΔHVR1  (2b/2a). 
           [0033]      FIG. 8  shows transfection to test efficacy of adaptive mutation C1446T on S52/JFH1 T2718G,T7160C,  and S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a). 
           [0034]      FIG. 9  shows transfection of ED43/JFH1 A2819G,A3269T,ΔHVR1  (4a/2a). 
           [0035]      FIG. 10  shows transfection of SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a). 
           [0036]      FIG. 11  shows transfection of HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a). 
           [0037]      FIG. 12  shows transfection of Huh7.5 cells with E2 N-terminal deletions of only 21 aa for H77/JFH1 T2700C,A4080T  (1a/2a) and ED43/JFH1 A2819G,A3269T  (4a/2a). 
           [0038]      FIG. 13  shows neutralization with HCV patient serum H06 for viruses with and without HVR1. 
           [0039]      FIG. 14  shows activity of HVR1 specific hyperimmune serum against H77/JFH1 T2700C,A4080T  (1a/2a) and H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a). 
           [0040]      FIG. 15  shows neutralization of HVR1 truncated viruses with IgG purified from serum H06 and also by HCV patient sera AA and SA3. 
           [0041]      FIG. 16  shows analysis of samples following ultracentrifugation. Specifically, RNA and infectivity titers of fractions with different densities for viruses: J6/JFH (2a/2a), J6/JFH ΔHVR1  (2a/2a), S52/JFH1 T2718G,T7160C  (3a/2a), S52/JFH1 (C1446T),T2718G,T7160C,ΔHVR1  (3a/2a), SA13/JFH1 C3405G,A3696G  (5a/2a), SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a) and HK6a/JFH1 T1389C,A1590G  (6a/2a) and HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a). 
       
    
    
       [0042]    The present invention will now be described in more detail in the following. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0043]    The present inventors advantageously provide hepatitis C virus (HCV) nucleotide sequences capable of replication, expression of functional HCV proteins and infection in vitro for development of antiviral therapeutics and prophylactics as well as diagnostics and prognostics. 
         [0044]    The present inventors developed H77/JFH1 T2700C,A4080T  (1a/2a), J4/JFH1 T2996C,A4827T,  (1b/2a), J6/JFH (2a/2a), J8/JFH1 (2b/2a), S52/JFH1 T2718G,T7160C  (3a/2a), SA13/JFH1 C3405G,A3696G  (5a/2a) and HK6a/JFH1 T1389C,A1590G  (6a/2a). These HCV recombinant viruses were used for the deletion of Hypervariable Region 1 (HVR1) to construct viable, JFH1-based genomes. This potentially allows for developing strategies for raising non-HVR1 based immune responses in patients as well as raising and testing antibodies against non-HVR1 epitopes. 
         [0045]    As is generally done within the art, all numerical references to specific mutations in a given genome (nucleic acid or amino acid) refers to numbering of the relevant reference sequence and therefore mutation numbers are not altered by deletions or insertions. More specifically, the HVR1 deletion of 78 or 81 nucleotides, corresponding to 26 or 27 amino acids, does not alter the downstream numbering of mutations. All references to specific mutations have been annotated according to this. Tables 1, 2, 3 and 4 list the coding envelope mutations identified for this application and are all numbered as described in this paragraph. 
         [0046]    In the present context a HCV strain containing adaptive mutations and/or deletions is written with these adaptive mutations and deletions in subscript i.e. a strain S52/JFH1 with cell culture adaptive mutations T2718G, T7160C and deletion of HVR1 (ΔHVR1) is denoted as S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a). If such strain acquires additional adaptive mutations that relate to the HVR1 deletion such adaptive mutations are written in subscript parenthesis i.e. a S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a) acquiring a C1446T adaptive mutation is denoted as S52/JFH1 (C1446T),T2718G,T7160C,ΔHVR1  (3a/2a). 
         [0047]    In the present context the terms “non-HVR1 epitopes”, “reference strains lacking HVR1”, “ΔHVR1”, and “deletion of HVR1” refer to an HCV genotype 1a, 1b, 2a, 2b, 3a, 4a, 5a, 6a or 7a in which the structural gene E2 has a deletion of at least part of HVR1. 
         [0048]    In the present context the term “genotype” is to be understood in accordance with Simmonds et al. 2005—i.e. the term “genotype” relate to the presently 7 identified major HCV genotypes. 
         [0049]    In the present context the term “subtype” is to be understood in accordance with Simmonds et al. 2005—in relation to e.g. genotype 1, this means, the presently identified subtypes indicated by lower-case letters; e.g. 1a, 1b etc. (Simmonds et al., 2005). 
         [0050]    In the present context the term “isolate” or “strain” is to be understood in accordance with Simmonds et al. 2005. Many different isolates/strains exist within a given genotype and subtype. An example of this is the H77 isolate/strain which is genotype 1, subtype a (abbreviated 1a) The terms “isolate” and “strain” are used herein interchangeably. 
         [0000]    Nucleic Acid Molecules (cDNA Clones and RNA Transcripts) 
         [0051]    In a broad aspect, the present invention is directed to genetically engineered hepatitis C virus (HCV) encoded by nucleic acid sequences such as complementary DNA (cDNA) sequences and replicating RNA comprising the structural gene E2 from HCV, wherein the structural gene E2 comprises a deletion of at least part of HVR1. 
         [0052]    Thus in one embodiment, the present invention relates to a replicating RNA comprising the structural gene E2 for human hepatitis C virus, wherein said structural gene E2 comprises a deletion of at least part of HVR1. 
         [0053]    In another embodiment the human hepatitis C virus is selected from the group consisting of strain H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J6/JFH1 ΔHVR1  (2a/2a), J8/JFH1 ΔHVR1  (2b/2a), S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a), HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) and QC69/JFH1 ΔHVR1  (7a/2a). 
         [0054]    In yet another embodiment the replicating RNA further comprises the structural genes (Core, E1 &amp; E2), p7 and the non-structural gene NS2 of genotypes 1a, 1b, 2a, 2b, 3a, 4a, 5a, 6a or 7a, and the non-structural genes NS3, NS4A, NS4B, NS5A and NS5B from the human hepatitis C virus genotype 2a strain JFH1. 
         [0055]    Deletion of at least part of HVR1 is to be understood as a deletion of an amino acid or amino acids N-terminally in HCV protein E2. N-terminally being defined as the first 30 amino acids in the E2 protein, such as the first 29 amino acids, e.g. the first 28 amino acids, such as the first 27 amino acids, e.g. the first 26 amino acids, such as the first 25 amino acids, e.g. the first 24 amino acids, such as the first 23 amino acids, e.g. the first 22 amino acids, such as the first 21 amino acids, e.g. the first 20 amino acids, such as the first 19 amino acids, e.g. the first 18 amino acids, such as the first 17 amino acids, e.g. the first 16 amino acids, such as the first 15 amino acids, e.g. the first 14 amino acids, such as the first 13 amino acids, e.g. the first 12 amino acids, such as the first 11 amino acids, e.g. the first 10 amino acids, such as the first 9 amino acids, e.g. the first 8 amino acids, such as the first 7 amino acids, e.g. the first 6 amino acids, such as the first 5 amino acids, e.g. the first 4 amino acids, such as the first 3 amino acids, e.g. the first 2 amino acids, such as the first amino acid of the E2 protein. This deletion could be of 26-27 amino acids as the one described here, but since the HVR1 epitopes recognized by the immune system could conceivably be located anywhere in the HVR1 sequence it is possible that smaller or larger deletions not yet attempted would yield very similar result. 
         [0056]    Thus, in one embodiment of the present invention the deletion may be of 30 amino acids, e.g. of 29 amino acids, such as of 28 amino acids, e.g. of 27 amino acids, such as of 26 amino acids, e.g. of 25 amino acids, such as of 25 amino acids, e.g. of 23 amino acids, such as of 22 amino acids, e.g. of 21 amino acids, such as of 20 amino acids, e.g. of 19 amino acids, such as of 18 amino acids, e.g. of 17 amino acids, such as of 16 amino acids, e.g. of 15 amino acids, such as of 14 amino acids, e.g. of 13 amino acids, such as of 12 amino acids, e.g. of 11 amino acids, such as of 10 amino acids, e.g. of 9 amino acids, such as of 8 amino acids, e.g. of 7 amino acids, such as of 6 amino acids, e.g. of 5 amino acids, such as of 4 amino acids, e.g. of 3 amino acids, such as of 2 amino acids, e.g. of 1 amino acid. As described under the possible effects of an HVR1 deletion of the HCV virus. This deletion could by of a single amino acid anywhere in the first 30 amino acids of E2 or it could be of multiple amino acids anywhere in this sequence. 
         [0057]    A replicating RNA is to be understood as a RNA inside an appropriate cell which can maintain its own replication, i.e. copying itself, by the help of endogenous encoded protein and/or cellular factors such as proteins and RNA. 
         [0058]    The structural gene E2 is to be understood as a HCV protein incorporated in the virus particle. This HCV protein is generally believed to be encoded as the third protein in the aforementioned polyprotein of HCV. The two upstream proteins being Core and E1. 
         [0059]    The invention provides isolated nucleic acid molecules encoding infectious recombinant HCV genomes, of which nucleic acid comprises intra- and intergenotypic HCV genomes. 
         [0060]    In one embodiment, the intra- or inter-genotypic HCV genomes comprises sequences encoding structural genes (Core, E1 and E2) comprising a deletion of at least part of HVR1 of E2, p7, the non-structural gene NS2 from a first HCV strain, and sequences encoding the non-structural genes NS3, NS4A, NS4B, NS5A, NS5B from a second HCV strain 
         [0061]    In one embodiment, the first HCV strain and the second HCV strain are from different genotypes. 
         [0062]    In one embodiment, the first HCV strain is strain H77 ΔHVR1 , J4 ΔHVR1 , J6 ΔHVR1 , J8 ΔHVR1 , S52 ΔHVR1 , SA13 ΔHVR1 , HK6a ΔHVR1  and QC69 ΔHVR1 , and in another embodiment, the second HCV strain is strain JFH1. 
         [0063]    The construction of all HVR1 deleted HCV virus coding plasmids was done by standard cloning techniques by the inventors. The N-terminal HVR1 deletions performed in HCV gene E2 was of 81 nucleotides encoding 27 amino acids in the case of genotypes 1a, 2a, 3a, 4a, 5a and 7a and of 78 nucleotides encoding 26 amino acids in the case of 6a. N-terminally are here defined as the first 30 amino acids in the E2 protein such as the first 29 amino acids, e.g. the first 28 amino acids, such as the first 27 amino acids, e.g. the first 26 amino acids, such as the first 25 amino acids, e.g. the first 24 amino acids, such as the first 23 amino acids, e.g. the first 22 amino acids, such as the first 21 amino acids, e.g. the first amino acids, such as the first 19 amino acids, e.g. the first 18 amino acids, such as the first 17 amino acids, e.g. the first 16 amino acids, such as the first 15 amino acids, e.g. the first 14 amino acids, such as the first 13 amino acids, e.g. the first 12 amino acids, such as the first 11 amino acids, e.g. the first 10 amino acids, such as the first 9 amino acids, e.g. the first 8 amino acids, such as the first 7 amino acids, e.g. the first 6 amino acids, such as the first 5 amino acids, e.g. the first 4 amino acids, such as the first 3 amino acids, e.g. the first 2 amino acids, such as the first amino acid in the E2 protein. 
         [0064]    Since the HVR1 epitopes recognized by the immune system could conceivably be located anywhere in the HVR1 sequence it is possible that smaller or larger deletions not yet attempted would yield very similar result as the ones described and also offer many of the same advantages in both neutralizing antibody production as well as vaccine development. It has been reported by Kato (1992) that HVR1 was shorter for genotype 1a and we therefore tested whether a shorter deletion of 21 aa would yield a viable virus in the case of genotype 1a. This turned out not to be the case. As described under the possible effects of an HVR1 deletion of the HCV virus, this deletion could be of a single amino acid anywhere in the first 30 amino acids of E2 or it could be of multiple amino acids anywhere in this sequence. 
         [0065]    In one embodiment, the HCV nucleic acid molecules of the present invention comprises the nucleic acid sequences (cDNA) of H77/JFH1 T2700C,A4080T,ΔHVR1  (SEQ ID NO 7), J6/JFH ΔHVR1  (SEQ ID NO 8), S52/JFH1 T2718G,T7160C,ΔHVR1  (SEQ ID NO 9), ED43/JFH1 A2819G,A3269T,ΔHVR1  (SEQ ID NO 10), SA13/JFH1 C3405G,A3696G,ΔHVR1  (SEQ ID NO 11) or HK6a/JFH1 T1389C,A1590G,ΔHVR1  (SEQ ID NO 12), J4/JFH1 T2996C,A4827T,ΔHVR1  (SEQ ID NO 19) and J8/JFH1 ΔHVR1  (SEQ ID NO 20). This deletion of HVR1 can be performed in all HCV constructs functioning in cell culture. Thus in another embodiment, the HCV nucleic acid sequence has 90% sequence identity to the strains mentioned above. 
         [0066]    In one embodiment the nucleic acid molecule comprises the nucleic acid molecule with a sequence identity of at least 90% to that of sequence SEQ ID NO 7, SEQ ID NO 8, SEQ ID NO 9, SEQ ID NO 10, SEQ ID NO 11, SEQ ID NO 12, SEQ ID NO 19 or SEQ ID NO 20. 
         [0067]    In another embodiment, the nucleic acid comprises a sequence sharing at least 90% identity with that set forth in SEQ ID NO 7, SEQ ID NO 8, SEQ ID NO 9, SEQ ID NO 10, SEQ ID NO 11, SEQ ID NO 12, SEQ ID NO 19 or SEQ ID NO 20, such as 90% identity, 91% identity, 92% identity, 93% identity, 94% identity, 95% identity, 96% identity, 97% identity, 98% identity, or 99% identity. 
       Sequence Identity 
       [0068]    As commonly defined “identity” is here defined as sequence identity between genes or proteins at the nucleotide or amino acid level, respectively. Thus, in the present context “sequence identity” is a measure of identity between proteins at the amino acid level and a measure of identity between nucleic acids at nucleotide level. The protein sequence identity may be determined by comparing the amino acid sequence in a given position in each sequence when the sequences are aligned. Similarly, the nucleic acid sequence identity may be determined by comparing the nucleotide sequence in a given position in each sequence when the sequences are aligned. 
         [0069]    To determine the percent identity of two amino acid sequences or of two nucleic acids, the sequences are aligned for optimal comparison purposes (e.g., gaps may be introduced in the sequence of a first amino acid or nucleic acid sequence for optimal alignment with a second amino or nucleic acid sequence). The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are identical at that position. The percent identity between the two sequences is a function of the number of identical positions shared by the sequences (i.e., % identity=# of identical positions/total # of positions (e.g., overlapping positions)×100). In one embodiment the two sequences are the same length. 
         [0070]    One may manually align the sequences and count the number of identical amino acids. Alternatively, alignment of two sequences for the determination of percent identity may be accomplished using a mathematical algorithm. Such an algorithm is incorporated into the NBLAST and XBLAST programs (Altschul et al., 1990). BLAST nucleotide searches may be performed with the NBLAST program, score=100, wordlength=12, to obtain nucleotide sequences homologous to a nucleic acid molecules of the invention. BLAST protein searches may be performed with the XBLAST program, score=50, wordlength=3 to obtain amino acid sequences homologous to a protein molecule of the invention. To obtain gapped alignments for comparison purposes, Gapped BLAST may be utilised. Alternatively, PSI-Blast may be used to perform an iterated search which detects distant relationships between molecules. When utilising the NBLAST, XBLAST, and Gapped BLAST programs, the default parameters of the respective programs may be used. See http://www.ncbi.nlm.nih.gov. Alternatively, sequence identity may be calculated after the sequences have been aligned e.g. by the BLAST program in the EMBL database (www.ncbi.nlm.gov/cgi-bin/BLAST). Generally, the default settings with respect to e.g. “scoring matrix” and “gap penalty” may be used for alignment. In the context of the present invention, the BLASTN and PSI BLAST default settings may be advantageous. 
         [0071]    In another embodiment the sequence identity is calculated on the sequence of the Core, E1, E2, p7 and NS2 the first HCV strain such as but not limited to H77, H77 ΔHVR1 , J4, J4 4ΔHVR1 , J6, J6 ΔHVR1 , J8, J8 ΔHVR1 , S52, S52 ΔHVR1 , SA13, SA13 ΔHVR1 , HK6a, HK6a ΔHVR1 , QC69 and QC69 ΔHVR1 . 
         [0072]    In another embodiment the sequence identity is calculated on the sequence of the 5′ UTR, NS3, NS4A, NS4B, NS5A, NS5B and 3′ UTR of JFH1. 
         [0073]    The percent identity between two sequences may be determined using techniques similar to those described above, with or without allowing gaps. In calculating percent identity, only exact matches are counted. 
         [0074]    It should be noted that while SEQ ID NO 7, SEQ ID NO 8, SEQ ID NO 9, SEQ ID NO 10, SEQ ID NO 11 SEQ ID NO 12, SEQ ID NO 19 and SEQ ID NO 20 are DNA sequences, the present invention contemplates the corresponding RNA sequence, and DNA and RNA complementary sequences as well. 
         [0075]    In a further embodiment, a region from an HCV isolate is substituted for a corresponding region, e.g., of an HCV nucleic acid having a sequence of SEQ ID SEQ ID NO 7, SEQ ID NO 8, SEQ ID NO 9, SEQ ID NO 10, SEQ ID NO 11, SEQ ID NO 12, SEQ ID NO 19 or SEQ ID NO 20. 
         [0076]    In another embodiment, the HCV nucleic acids is a DNA that codes on expression or after in vitro transcription for a replication-competent HCV RNA genome, or is itself a replication-competent HCV RNA genome. 
         [0077]    In one embodiment, the HCV nucleic acid of the invention has a full-length sequence as depicted in or corresponding to SEQ ID NO 7, SEQ ID NO 8, SEQ ID NO 9, SEQ ID NO 10, SEQ ID NO 11, SEQ ID NO 12, SEQ ID NO 19 or SEQ ID NO 20. Various modifications for example of the 5′ and 3′ UTR are also contemplated by the invention. In another embodiment, the nucleic acid further comprises a reporter gene, which, in one embodiment, is a gene encoding neomycin phosphotransferase, Renilla luciferase, secreted alkaline phosphatase (SEAP), Gaussia luciferase or fluorescent proteins, such as enhanced green fluorescent protein (EGFP). 
         [0078]    Naturally, as noted above, the HCV nucleic acid sequence of the invention is selected from the group consisting of double stranded DNA, positive-sense cDNA, or negative-sense cDNA, or positive-sense RNA or negative-sense RNA or double stranded RNA. Thus, where particular sequences of nucleic acids of the invention are set forth, both DNA and corresponding RNA are intended, including positive and negative strands thereof. 
         [0079]    In a further embodiment, the nucleic acid sequence of SEQ ID NO 7, SEQ ID NO 8, SEQ ID NO 9, SEQ ID NO 10, SEQ ID NO 11, SEQ ID NO 12, SEQ ID NO 19 or SEQ ID NO 20 or the said nucleic acid sequence with any mutation described in this document is obtained by any other means than what is described above. 
         [0080]    In an embodiment, the complementary DNAs (cDNA) provided by the present invention encodes human hepatitis C virus of strain: 
         [0000]    H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a) J6/JFH ΔHVR1  (2a/2a), J8/JFH1 ΔHVR1  (2b/2a), S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), ED43/JFH1 A2819G,A3269T,ΔHVR1  (4a/2a), SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a), HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) or QC69/JFH1 ΔHVR1  (7a/2a)
       wherein said molecule is capable of expressing said virus, when transfected into cells, and further capable of infectivity in vivo   wherein H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 1,   wherein J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 22   wherein J6/JFH1 ΔHVR1  (2a/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 2,   wherein J8/JFH1 ΔHVR1  (2b/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 23   wherein S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 3,   wherein ED43/JFH1 A2819G,A3269T,ΔHVR1  (4a/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 4,   wherein SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 5 and,   wherein HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 6.       
 
         [0090]    In another embodiment, the amino acid sequences comprises a sequence sharing at least 90% identity with that set forth in SEQ ID NO 1, SEQ ID NO 2, SEQ ID NO 3, SEQ ID NO 4, SEQ ID NO 5, SEQ ID NO 6, SEQ ID NO 22 or SEQ ID NO 23 such as 91% identity, 92% identity, 93% identity, 94% identity, 95% identity, 96% identity, 97% identity, 98% identity, or 99% identity. 
         [0091]    It should be understood that a sequence identity of at least 90%, such as 90% identity, 91% identity, 92% identity, 93% identity, 94% identity, 95% identity, 96% identity, 97% identity, 98% identity, or 99% identity applies to all sequences disclosed in the present application. 
         [0092]    In an embodiment of the present invention H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a) comprises the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 7. 
         [0093]    In a further embodiment of the present invention J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a) comprises the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 19. 
         [0094]    In yet an embodiment of the present invention J6/JFH1 ΔHVR1  (2a/2a) comprises the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 8. 
         [0095]    In another embodiment of the present invention J8/JFH1 ΔHVR1  (2b/2a) comprises the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 20. 
         [0096]    In a further embodiment of the present invention S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a) comprises the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 9. 
         [0097]    In yet an embodiment of the present invention ED43/JFH1 A2819G,A3269T,ΔHVR1  (4a/2a) comprises the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 10. 
         [0098]    In another embodiment of the present invention SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a) comprises the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 11. 
         [0099]    In a further embodiment of the present invention HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) comprises the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 12. 
         [0100]    According to various aspects of the invention, HCV nucleic acid, including the polyprotein coding region, can be mutated or engineered to produce variants or derivatives with, e.g., silent mutations, conservative mutations, etc. In a further preferred aspect, silent nucleotide changes in the polyprotein coding regions (i.e., variations of the second or third base of a codon that encodes the same amino acid) are incorporated as markers of specific HCV clones. 
         [0101]    Thus, one aspect of the present invention relates to any of the amino acid sequences disclosed herein, such as but not limited to SEQ ID NO 1, 2, 3, 4, 5, 6, 22 and 23. 
         [0102]    Nucleic acid molecules according to the present invention may be inserted in a plasmid vector for translation of the corresponding HCV RNA. Thus, the HCV DNA may comprise a promoter 5′ of the 5′-UTR on positive-sense DNA, whereby transcription of template DNA from the promoter produces replication-competent RNA. The promoter can be selected from the group consisting of a eukaryotic promoter, yeast promoter, plant promoter, bacterial promoter, or viral promoter. 
         [0103]    In one embodiment the present invention provides a cassette vector for cloning viral genomes, comprising, inserted therein, the nucleic acid sequence according to the invention and having an active promoter upstream thereof. 
       HVR1 Deletion 
       [0104]    Deletion of HVR1 may and may not affect infectivity of HCV in vitro and in vivo. It may affect the type of immune response generated by a suitable host upon infection with HCV lacking HVR1. It may affect the epitopes targeted by the immune system of the suitable host. It may affect outcome of an HCV infection of a suitable host. If HVR1 deletion has an effect on this outcome this effect could be reduced pathogenicity of HCV, reduced titers of HCV in the blood and/or soft tissues of the suitable host, higher occurrence of spontaneous clearance of the infection. It may render the virus more susceptible to treatment of both a prophylactic as well as a therapeutic nature. All the above-mentioned possibilities may differ between the individual genotypes. They may be more severe for particular genotypes than for others. Some of the above considerations may not apply to particular genotypes, but may still hold true for others. Deletion of amino acids downstream of HVR1 either with or without a concurrent deletion of HVR1 may have effects similar to the possibilities described above. If multiple amino acids immediately downstream of HVR1 are deleted then at some point the virus will likely become non-infectious as is described for J6/JFH ΔHVR1  (2a/2a) in example 2. In example 2 additional amino acids are removed and upon the removal of a total of 30 N-terminal amino acids in E2 the virus becomes non-infectious. 
         [0105]    HVR1 may be deleted by fusion PCR, standard cloning techniques or by commercially available kits. 
         [0106]    The present inventors indicate a decoy function of HVR1, and add credence to this hypothesis by the following findings: Most HCV genotypes retain in vitro infectivity after HVR1 deletion that in some cases rivals that of the parental virus (original non-HVR1 deleted). These data support the hypothesis of a decoy function of HVR1 since they show that HVR1 is not required for viral infectivity. 
       Adaptive Mutations 
       [0107]    Adapted mutants of a HCV-cDNA construct or HCV-RNA full-length genome with improved abilities to generate infectious viral particles in cell culture compared to the original HCV-cDNA construct or the original HCV-RNA full-length genome are characterized in that they are obtainable by a method in which the type and number of mutations in a cell culture adapted HCV-RNA genome are determined through sequence analysis and sequence comparison and these mutations are introduced into a HCV-cDNA construct, particularly a HCV-cDNA construct according to the present invention, or into an (isolated) HCV-RNA full-length genome, either by site-directed mutagenesis, or by exchange of DNA fragments containing the relevant mutations. 
         [0108]    The adaptive mutations present in the constructs prior to HVR1 deletion for the following recombinant viruses: H77/JFH1 T2700C,A4080T  (1a/2a), J4/JFH1 T2996C,A4827T  (1b/2a), S52/JFH1 T2718G,T7160C  (3a/2a), SA13/JFH1 C3405G,A3696G  (5a/2a) and HK6a/JFH1 T1389C,A1590G  (6a/2a) are the basis for the viability of these constructs in the cell culture system. They adapt the virus thereby improving the infection capacity of the given HCV recombinant. In the case of J6/JFH (2a/2a) and J8/JFH1 (2b/2a) the viruses did not require mutations adapting them to spread in cell culture. These viruses were the specific basis for the generation of the HVR1 deleted viruses, but any HCV genome able to replicate in cell culture would very likely have served. The main point being that in order to investigate the effect of an HVR1 deletion on infectivity, the virus has to be infectious to begin with (meaning before deletion of HVR1). 
         [0109]    The degree of infectivity is described elsewhere in this document (examples 1 and 3 and Table 5). By using the aforementioned specific recombinant viruses, cell culture adapted and as such viable, the inventors generated and serially passaged HCV recombinants of the following HVR1 deleted constructs: 
         [0000]    H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J6/JFH1 ΔHVR1  (2a/2a), J8/JFH1 ΔHVR1  (2b/2a), S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a) and HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a). Of these H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J8/JFH1 ΔHVR1  (2b/2a) and S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a) acquired additional coding mutations in HCV genes E1 and E2 either in transfection or in serial passages (see example 3 and tables 1-4). 
         [0110]    The identified coding envelope mutations were A1122G, T1383G, T1421C, A1628G, A1671G, A1766G, T2385A and C2538T for H77/JFH1 T2700C,A4080T,ΔHVR1  A1236G, C1428T, A1643C, A2066G, G2225G and G2468C for J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), C1571G, T1572G, T1574A, A1580G, A1652T and A1941C for J8/JFH1 ΔHVR1,T1574A  (2b/2a), and finally C1446T for S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a). Of these A1122G, A1671G, A1766G, C2538T, T1574A and C1446T were tested in reverse genetic studies by engineering the mutations into the original HVR1 deleted constructs. All were found to improve infectivity of the respective HVR1 deleted viruses. More specifically it was possible to increase kinetics, infectivity titers and viral spread by introducing A1122G, A1671G, A1766G and C2538T into H77/JFH1 T2700c,A4080T,ΔHVR1  singly or in combinations of two, T1574A into J8/JFH1 ΔHVR1  and C1446T into S52/JFH1 T2718G,T7160C,ΔHVR1 . 
         [0111]    The present inventors here report adaptive mutations following deletion of HVR1 in the structural E1 or E2 domain, which allow efficient formation and release of viral particles in cell culture. Other adaptive mutations in either E1 or E2 serving the same purpose, that purpose being the adaptation of HVR1 deleted virus, are expected to exist and a number of putative adaptive mutations are listed in table 1-4 (in the present context termed merely adaptive mutations). Thus the present invention relates to these specific as well as of yet unknown adaptive mutations with similar HVR1 adapting capabilities in the present use as well as use in other strains by changing equivalent positions of such genomes to the adapted nucleotide or amino acid described. 
         [0112]    In the present invention, the adaptive mutations that are of importance are mutations relating to the deletion of HVR1. The deletion of at least part of HVR1 in combination with these adaptive mutations could potentially be transferred to any HCV construct viable in cell culture and after the transfer still be viable. 
         [0113]    A group of preferred HCV-cDNA constructs with the ability to release viral particles in cell culture, which are consequently highly suitable for practical use, are characterized in that they contain one, several or all of the nucleic acid changes listed below and/or one or several or all of the following amino acid exchanges. 
         [0114]    It should be understood that any feature and/or aspect discussed above in connection with the mutations according to the invention apply by analogy to both single mutation and any combination of the mutations. 
         [0115]    One embodiment of the present invention relates to adaptive mutations, wherein the adaptive mutation is a mutation that can be observed by clonal or direct sequencing of recovered replicating genomes of SEQ ID NO 16, 17, 18 and 21. 
         [0116]    In a further embodiment, the present invention relates to nucleic acid molecules according to the present invention, wherein said molecule comprises one or more adaptive mutations in the envelope genes E1 or E2, singly or in combination. 
         [0117]    In one embodiment the present invention relates to a replicating RNA comprising the structural gene E2 from human hepatitis C virus, wherein the structural gene E2 comprises a deletion of at least part of HVR1, wherein the human hepatitis C virus is selected from the group consisting of strain H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J6/JFH1 ΔHVR1  (2a/2a), J8/JFH 1 ΔHVR1  (2b/2a), S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), ED43/JFH1 A2819G,A3269T,ΔHVR1  (4a/2a), SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a), HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) and QC69/JFH1 ΔHVR1  (7a/2a) and wherein the replicating RNA comprises the structural genes (Core, E1 &amp; E2), p7 and the non-structural gene NS2 of genotypes 1a, 1b, 2a, 2b, 3a, 4a, 5a or 6a, and the non-structural genes NS3, NS4A, NS4B, NS5A and NS5B from the human hepatitis C virus genotype 2a strain JFH1. 
         [0118]    In yet an embodiment the present invention pertains to an isolated nucleic acid molecule, which encodes human hepatitis C virus of strain: H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J6/JFH1 ΔHVR1  (2a/2a), J8/JFH1 ΔHVR1  (2b/2a), S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a), HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) or QC69/JFH1 ΔHVR1  (7a/2a)
       wherein said molecule is capable of expressing said virus, when transfected into cells, and   wherein H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 1,   wherein J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 22,   wherein J6/JFH1 ΔHVR1  (2a/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 2,   wherein J8/JFH1 ΔHVR1  (2b/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 23,   wherein S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 3,   wherein SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 5 and,   wherein HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 6.       
 
         [0127]    In a further embodiment H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a) comprises the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 7. 
         [0128]    In yet an embodiment J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a) comprises the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 19. 
         [0129]    In an embodiment J6/JFH1 ΔHVR1  (2a/2a) comprises the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 8. 
         [0130]    In a still further embodiment J8/JFH1 ΔHVR1  (2b/2a) comprises the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 20. 
         [0131]    In yet an embodiment S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a) comprises the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 9. 
         [0132]    In an embodiment SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a) comprises the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 11. 
         [0133]    In a still further embodiment HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) comprises the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 12. 
         [0134]    Furthermore the present invention pertains to a nucleic acid molecule wherein H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J6/JFH ΔHVR1  (2a/2a), J8/JFH1 ΔHVR1  (2b/2a), S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a), HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) and/or QC69/JFH1 ΔHVR1  (7a/2a) comprises one or more adaptive mutations in HCV proteins E1 and E2. 
         [0135]    In one embodiment the one or more adaptive mutations in H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a) is at least one of the replacements of the first said nucleotide of SEQ ID NO 7 by the following said nucleotide selected from the group consisting of A1122G, A1671G, A1766G and C2538T. 
         [0136]    In another embodiment the one or more adaptive mutations in H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a) is at least one of the replacements of the first said nucleotide of SEQ ID NO 7 by the following said nucleotide selected from the group consisting of T1383G, T1421C, A1628G and T2385A. 
         [0137]    In one embodiment the one or more adaptive mutations in H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a) is at least one of the replacements of the first said nucleotide of SEQ ID NO 7 by the following said nucleotide selected from the group consisting of A1122G, A1671G, A1766G, C2538T, T1383G, T1421C, A1628G and T2385A. 
         [0138]    In a further embodiment the one or more adaptive mutations in H77/JFH1 V787A,Q1247L,ΔHVR1  (1a/2a) is at least one of the replacements of the first said amino acid of SEQ ID NO 1 by the following said amino acid selected from the group consisting of H261R, Q444R, N476D and S733F. 
         [0139]    In yet an embodiment the one or more adaptive mutations in H77/JFH1 V787A,Q1247L,ΔHVR1  (1a/2a) is at least one of the replacements of the first said amino acid of SEQ ID NO 1 by the following said amino acid selected from the group consisting of I348S, Y361H, N430D and L682Q. 
         [0140]    In a further embodiment the one or more adaptive mutations in H77/JFH1 V787A,Q1247L,ΔHVR1  (1a/2a) is at least one of the replacements of the first said amino acid of SEQ ID NO 1 by the following said amino acid selected from the group consisting of H261R, Q444R, N476D, S733F, I348S, Y361H, N430D and L682Q. 
         [0141]    In a still further embodiment the one or more adaptive mutations in J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a) is at least one of the replacements of the first said nucleotide of SEQ ID NO 19 by the following said nucleotide selected from the group consisting of A1236G, C1428T, A1643C, A2066G, G2225A and G2468C. 
         [0142]    In an embodiment the one or more adaptive mutations in J4/JFH1 F886L,Q1496LΔHVR1  (1b/2a) is at least one of the replacements of the firstsaid amino acid of SEQ ID NO 22 by the following said amino acid selected from the group consisting of E299G, S363F, T435P, N576D, V629I and V710L. 
         [0143]    In a further embodiment the one or more adaptive mutations in J8/JFH1 ΔHVR1  (2b/2a) is at least one of the replacements of the first said nucleotide of SEQ ID NO 20 by the following said nucleotide selected from the group consisting of T1574A. 
         [0144]    In yet an embodiment the one or more adaptive mutations in J8/JFH1 ΔHVR1  (2b/2a) is at least one of the replacements of the first said nucleotide of SEQ ID NO 20 by the following said nucleotide selected from the group consisting of C1571G, T1572G, A1580G, A1652T and A1941C. 
         [0145]    In a further embodiment the one or more adaptive mutations in J8/JFH1 ΔHVR1  (2b/2a) is at least one of the replacements of the first said nucleotide of SEQ ID NO 20 by the following said nucleotide selected from the group consisting of T1574A, C1571G, T1572G, A1580G, A1652T and A1941C. 
         [0146]    In a still further embodiment the one or more adaptive mutations in J8/JFH1 ΔHVR1  (2b/2a) is at least one of the replacements of the first said amino acid of SEQ ID NO 23 by the following said amino acid selected from the group consisting of Y412N. 
         [0147]    In an embodiment the one or more adaptive mutations in J8/JFH1 ΔHVR1 ( 2b/2a) is at least one of the replacements of the first said amino acid of SEQ ID NO 23 by the following said amino acid selected from the group consisting of L411V, L411R, I414V, M438L and N534T. 
         [0148]    In a still further embodiment the one or more adaptive mutations in J8/JFH1 ΔHVR1  (2b/2a) is at least one of the replacements of the first said amino acid of SEQ ID NO 23 by the following said amino acid selected from the group consisting of Y412N, L411V, L411R,1414V, M438L and N534T. 
         [0149]    In yet an embodiment the one or more adaptive mutationsstrain S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a) is at least one of the replacements of the first said nucleotide of SEQ ID NO 9 by the following said nucleotide selected from the group consisting of C1446T. 
         [0150]    In a further embodiment the one or more adaptive mutations in S52/JFH1 I793S,S2274P,ΔHVR1  (3a/2a) is at least one of the replacements of the first said amino acid of SEQ ID NO 3 by the following said amino acid from the group consisting of A369V. 
         [0151]    In a further embodiment the invention relates to an isolated nucleic acid molecule, which encodes human hepatitis C virus of strain H77/JFH1 V787A,Q1247L,ΔHVR1  (1a/2a), wherein the molecule is capable of expressing said virus, when transfected into cells, and wherein H77/JFH1 V7S7A,Q1247L,ΔHVR1  (1a/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 1, and the adaptive mutation in H77/JFH1 V787A,Q1247L,ΔHVR1  (1a/2a) is at least one of the replacements of the first said amino acid at the said position of H77/JFH1 V787A,Q1247L  in SEQ ID NO 1 by the following said amino acid selected from the group consisting of H261R, Q444R, N476D and S733F. 
         [0152]    In one embodiment the present invention pertains to an isolated nucleic acid molecule which encodes human hepatitis C virus of strain H77/JFH1 V787A,Q1247L,ΔHVR1 , wherein said molecule:
       (i) is capable of expressing said virus when transfected into cells,   (ii) is capable of infectivity in vivo,   (iii) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 1, which   (iv) comprises at least one adaptive mutation in the amino acid sequence of E1 or E2 selected from the group consisting of H261R, Q444R, N476D and S733F.       
 
         [0157]    In one embodiment the present invention pertains to an isolated nucleic acid molecule which encodes human hepatitis C virus of strain H77/JFH1 V787A,Q1247L,ΔHVR1  wherein said molecule:
       (i) is capable of expressing said virus when transfected into cells,   (ii) is capable of infectivity in vivo,   (iii) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 1, which   (iv) comprises at least one adaptive mutation in the amino acid sequence of E1 or E2 selected from the group consisting of I348S, Y361H, N430D and L682Q.       
 
         [0162]    In one embodiment the amino acid sequence of SEQ ID NO 1 comprises at least one adaptive mutation in the amino acid sequence of E1 or E2 selected from the group consisting of I348S, Y361H, N430D, L682Q, H261R, Q444R, N476D and S733F. 
         [0163]    In particular the amino acid sequence H77/JFH1 (H261R,Q444R),V787A,Q1247L,ΔHVR1  (1a/2a) SEQ ID NO 13 and H77/JFH1 (N476D,S733F),V787A,Q1247L,ΔHVR1  (1a/2a) SEQ ID NO 14. 
         [0164]    One embodiment of the invention relates to an isolated nucleic acid molecule, which encodes human hepatitis C virus of strain H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), wherein the molecule is capable of expressing said virus, when transfected into cells, and wherein H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a) is encoded by the nucleotide sequence with a sequence identity of at least 90% to that of SEQ ID NO 7, and the adaptive mutation in H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a) is at least one of the replacements of the first said nucleotide at the said position of SEQ ID NO 7 by the following said nucleotide selected from the group consisting of A1122G, A1671G, A1766G and C2538T. In particular the nucleotide sequence H77/JFH1 (A1122G,A1671G),T2700C,A4080T,ΔHVR1  (1a/2a) SEQ ID NO 16 and H77/JFH1 (A1766G,C2538T),T2700C,A4080T,ΔHVR1  (1a/2a) SEQ ID NO 17. 
         [0165]    In one embodiment the present invention pertains to an isolated nucleic acid molecule which encodes human hepatitis C virus of strain H77/JFH1 V87A,Q1247L,ΔHVR 1 wherein said molecule:
       (i) is capable of expressing said virus when transfected into cells,   (ii) is capable of infectivity in vivo,   (iii) encodes the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 7, which   (iv) comprises at least one adaptive mutation in the nucleic acid sequence of E1 or E2 selected from the group consisting of A1122G, A1671G, A1766G and C2538T.       
 
         [0170]    In one embodiment the present invention pertains to an isolated nucleic acid molecule which encodes human hepatitis C virus of strain H77/JFH1 V787A,Q1247L,ΔHVR1  wherein said molecule:
       (i) is capable of expressing said virus when transfected into cells,   (ii) is capable of infectivity in vivo,   (iii) encodes the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 7, which   (iv) comprises at least one adaptive mutation in the nucleic acid sequence of E1 or E2 selected from the group consisting of T1383G, T1421C, A1628G and T2385A.       
 
         [0175]    In one embodiment the nucleic acid sequence of SEQ ID NO 7 comprises at least one adaptive mutation in the nucleic acid sequence of E1 or E2 selected from the group consisting of A1122G, A1671G, A1766G, C2538T T1383G, T1421C, A1628G and T2385A. 
         [0176]    One embodiment of the invention relates to an isolated nucleic acid molecule, which encodes human hepatitis C virus of strain J8/JFH1 ΔHVR1  (2b/2a), wherein the molecule is capable of expressing said virus, when transfected into cells, and wherein J8/JFH1 ΔHVR1  (2b/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 23, and the adaptive mutation in J8/JFH1 ΔHVR1  (2b/2a) is at least one of the replacements of the first said amino acid at the said position of SEQ ID NO 23 by the following said amino acid selected from the group consisting of Y412N. In particular the amino acid sequence J8/JFH1 (V412N),ΔHVR1  (2b/2a), SEQ ID NO 24. 
         [0177]    In one embodiment the present invention pertains to an isolated nucleic acid molecule which encodes human hepatitis C virus of strain J8/JFH1 ΔHVR1  (2b/2a), wherein said molecule:
       (i) is capable of expressing said virus when transfected into cells,   (ii) is capable of infectivity in vivo,   (iii) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 23, which   (iv) comprises at least one adaptive mutation in the amino acid sequence of E1 or E2 selected from the group consisting of Y412N.       
 
         [0182]    In one embodiment the present invention pertains to an isolated nucleic acid molecule which encodes human hepatitis C virus of strain J8/JFH1 ΔHVR1  (2b/2a), wherein said molecule:
       (i) is capable of expressing said virus when transfected into cells,   (ii) is capable of infectivity in vivo,   (iii) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 23, which   (iv) comprises at least one adaptive mutation in the amino acid sequence of E1 or E2 selected from the group consisting of L411V, L411R,1414V, M438L and N534T.       
 
         [0187]    In one embodiment the amino acid sequence of SEQ ID NO 23 comprises at least one adaptive mutation in the amino acid sequence of E1 or E2 selected from the group consisting of Y412N, L411V, L411R,1414V, M438L and N534T. 
         [0188]    One embodiment of the invention relates to an isolated nucleic acid molecule, which encodes human hepatitis C virus of strain J8/JFH1 ΔHVR1  (2b/2a), wherein the molecule is capable of expressing said virus, when transfected into cells, and wherein J8/JFH1 ΔHVR1  (2b/2a) is encoded by the nucleotide sequence with a sequence identity of at least 90% to that of SEQ ID NO 20, and the adaptive mutation in J8/JFH1 ΔHVR1  (2b/2a) is at least one of the replacements of the first said nucleotide at the said position of SEQ ID NO 20 by the following said nucleotide selected from the group consisting of T1574A. In particular the nucleotide sequence J8/JFH1 (T1574A),ΔHVR1  (2b/2a) SEQ ID NO 21. 
         [0189]    In one embodiment the present invention pertains to an isolated nucleic acid molecule which encodes human hepatitis C virus of strain J8/JFH1 ΔHVR1  (2b/2a), wherein said molecule:
       (i) is capable of expressing said virus when transfected into cells,   (ii) is capable of infectivity in vivo,   (iii) encodes the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 20, which   (iv) comprises at least one adaptive mutation in the nucleic acid sequence of E1 or E2 selected from the group consisting of T1574A.       
 
         [0194]    In one embodiment the present invention pertains to an isolated nucleic acid molecule which encodes human hepatitis C virus of strain J8/JFH1 ΔHVR1  (2b/2a), wherein said molecule:
       (i) is capable of expressing said virus when transfected into cells,   (ii) is capable of infectivity in vivo,   (iii) encodes the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 20, which   (iv) comprises at least one adaptive mutation in the nucleic acid sequence of E1 or E2 selected from the group consisting of C1571G, T1572G, A1580G, A1652T and A1941C.       
 
         [0199]    In one embodiment the nucleic acid sequence of SEQ ID NO 20 comprises at least one adaptive mutation in the nucleic acid sequence of E1 or E2 selected from the group consisting of T1574A, C1571G, T1572G, A1580G, A1652T and A1941C. 
         [0200]    One embodiment of the invention relates to an isolated nucleic acid molecule, which encodes human hepatitis C virus of strain S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), wherein the molecule is capable of expressing said virus, when transfected into cells, and wherein S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 3, and the adaptive mutation in S52/JFH1 T2718G,T7160C,ΔHVR1  is at least one of the replacements of the first said amino acid at the said position of SEQ ID NO 3 by the following said amino acid selected from the group consisting of A369V. In particular the amino acid sequence S52/JFH1 (A369V),I793S,S2274P,ΔHVR1  (3a/2a), SEQ ID NO 15. 
         [0201]    In one embodiment the present invention pertains to an isolated nucleic acid molecule which encodes human hepatitis C virus of strain S52/JFH1 T2718G,T7160C,ΔHVR1  wherein said molecule:
       (i) is capable of expressing said virus when transfected into cells,   (ii) is capable of infectivity in vivo,   (iii) encodes the amino acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 3, which   (iv) comprises at least one adaptive mutation in the amino acid sequence of E1 or E2 selected from the group consisting of A369V.       
 
         [0206]    One embodiment of the invention relates to an isolated nucleic acid molecule, which encodes human hepatitis C virus of strain S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), wherein the molecule is capable of expressing said virus, when transfected into cells, and wherein S52/JFH1 T271sG,T7160C,ΔHVR1  (3a/2a) is encoded by the nucleotide sequence with a sequence identity of at least 90% to that of SEQ ID NO 9, and the adaptive mutation in S52/JFH1 T271sG,T7160C,ΔHVR1  is at least one of the replacements of the first said nucleotide at the said position of SEQ ID NO 9 by the following said nucleotide selected from the group consisting of C1446T. In particular the nucleotide sequence S52/JFH1 (C1446T),T2718G,T7160C,ΔHVR1  (3a/2a), SEQ ID NO 18. 
         [0207]    In one embodiment the present invention pertains to an isolated nucleic acid molecule which encodes human hepatitis C virus of strain S52/JFH1 T2718G,T7160C,ΔHVR1 , wherein said molecule:
       (i) is capable of expressing said virus when transfected into cells,   (ii) is capable of infectivity in vivo,   (iii) encodes the nucleic acid sequence with a sequence identity of at least 90% to that of SEQ ID NO 9, which   (iv) comprises at least one adaptive mutation in the nucleic acid sequence of E1 or E2 selected from the group consisting of C1446T.       
 
         [0212]    In another embodiment all the amino acid changes observed herein are provided by the present application. The skilled addressee can easily obtain the same amino acid change by mutating another base of the codon and hence all means of obtaining the given amino acid sequence is intended. 
         [0213]    Finally, it would be interesting to elucidate the mechanism of action of the identified mutations. It is most likely, that they compensate for deletion of HVR1, facilitating the restoration of a fully functional E2 protein. In principle they might enable efficient intergenotypic protein interaction and/or lead to improvement of protein function independent of these intergenotypic interactions, for example by influencing interactions with host cell proteins. 
         [0214]    HVR1 deleted JFH1-based recombinants of genotype 4a E2 protein deleted of HVR1 is expressed in the ED43/JFH1 A2819G,A3269T,ΔHVR1  (4a/2a) transfected cells and as such recombinant protein could be purified from this and used for the stated purposes of prophylactic and therapeutic vaccine development in spite of the great attenuation of the virus upon HVR1 deletion. The present inventors investigated if a shorter, 21 aa deletion of N-terminal aa of E2 would allow for less attenuation. This was not the case (see example 4 for details). 
         [0215]    HVR1 deleted JFH1-based recombinants of genotype 7aIt is likely that QC69/JFH1 ΔHVR1  (7a/2a) with a deletion of at least part of HVR1 will be or adapt to being viable like it has here been described for H77/JFH1 T2700c,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2906C,A4827T,ΔHVR1  (1b/2a), J6/JFH1 ΔHVR1  (2a/2a), J8/JFH1 ΔHVR1  (2b/2a), S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a) and HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a). 
         [0216]    HVR1 deleted JFH1-based recombinants of other subtypes (eg. b, c, etc) It is likely that deletion of HVR1 of other HCV subtype JFH1-based recombinants would result in production of viable virus and that envelope mutations mentioned herein that arose upon HVR1 deletion will prove important in the adaptation of such HCV virus constructs. 
       Titers 
       [0217]    To determine the efficiency of the developed system, HCV RNA titers are determined in IU/ml (international units/ml) with Taq-Man Real-Time-PCR and infectious titers are determined with a tissue culture infectious dose 50% method. This titer indicates the dilution of the examined viral stock, at which 50% of the replicate cell cultures used in the assay become infected and is given in TCID 50 /ml or by Focus Forming Unit (FFU) infectivity assays in which the number of infected foci are simply counted and used in the calculation of virus titer. 
         [0218]    One embodiment of the present invention relates to a nucleic acid molecule of the present invention, wherein said molecule is capable of generating a HCV RNA titer of 10 4  IU/ml or above following transfection and/or subsequent viral passage, such as a titer of at least 10 5  IU/mL, such as a titer of at least 10 6  IU/mL, such as a titer of at least 10 7  IU/mL, such as a titer of at least 10 8  IU/mL, such as a titer of at least 10 9  IU/mL, such as a titer of at least 10 10  IU/mL, such as a titer of at least 10 11  IU/mL, or such as a titer of at least 10 12  IU/mL. 
         [0219]    In another embodiment, the present invention relates to a nucleic acid molecule according to the invention, wherein said molecule is capable of generating a HCV infectivity titer of at least 10 2  TCID 50 /ml or above following transfection and/or subsequent viral passage, such as a titer of at least 10 3  TCID50/ml, such as a titer of at least 10 4  TCID 50 /ml, such as a titer of at least 10 5  TCID 50 /ml, such as a titer of at least 10 6  TCID 50 /ml, such as a titer of at least 10 7  TCID 50 /ml, such as a titer of at least 10 8  TCID 50 /ml, such as a titer of at least 10 9  TCID 50 /ml or such as a titer of at least 10 10  TCID 50 /ml. 
         [0220]    In another embodiment, the present invention relates to a nucleic acid molecule according to the invention, wherein said molecule is capable of generating a HCV infectivity titer of at least 10 2  FFUs/ml or above following transfection and/or subsequent viral passage, such as a titer of at least 10 3  FFUs/ml, such as a titer of at least 10 4  FFUs/ml, such as a titer of at least 10 5  FFUs/ml, such as a titer of at least 10 6  FFUs/ml, such as a titer of at least 10 7  FFUs/ml, such as a titer of at least 10 8  FFUs/ml, such as a titer of at least 10 9  FFUs/ml or such as a titer of at least 10 10  FFUs/ml. 
         [0221]    It is of course evident to the skilled addressee that the titers described here are obtained using the assay described in this text. Any similar or equivalent titer determined by any method is thus evidently within the scope of the present invention. 
       Compositions 
       [0222]    One embodiment of the present invention relates to a composition comprising a nucleic acid molecule according to the invention suspended in a suitable amount of a pharmaceutical acceptable diluent or excipient. 
         [0223]    In another embodiment, this invention provides for compositions comprising an isolated nucleic acid, vector or cell of this invention, or an isolated nucleic acid obtained via the methods of this invention. 
         [0224]    In one embodiment, the term “composition” refers to any such composition suitable for administration to a subject, and such compositions may comprise a pharmaceutically acceptable carrier or diluent, for any of the indications or modes of administration as described. The active materials in the compositions of this invention can be administered by any appropriate route, for example, orally, parenterally, intravenously, intradermally, subcutaneously, or topically, in liquid or solid form. 
         [0225]    It is to be understood that any applicable drug delivery system may be used with the compositions and/or agents/vectors/cells/nucleic acids of this invention, for administration to a subject, and is to be considered as part of this invention. 
         [0226]    The compositions of the invention can be administered as conventional HCV therapeutics. The compositions of the invention may include more than one active ingredient, which interrupts or otherwise alters groove formation, or occupancy by RNA or other cellular host factors, in one embodiment, or replicase components, in another embodiment, or zinc incorporation, in another embodiment. 
         [0227]    The precise formulations and modes of administration of the compositions of the invention will depend on the nature of the anti-HCV agent, the condition of the subject, and the judgment of the practitioner. Design of such administration and formulation is routine optimization generally carried out without difficulty by the practitioner. 
         [0228]    It is to be understood that any of the methods of this invention, whereby a nucleic acid, vector or cell of this invention is used, may also employ a composition comprising the same as herein described, and is to be considered as part of this invention. 
         [0229]    “Pharmaceutically acceptable” refers to molecular entities and compositions that are physiologically tolerable and do not typically produce an allergic or similar untoward reaction, such as gastric upset, dizziness and the like, when administered to a human. Preferably, as used herein, the term “pharmaceutically acceptable” means approved by a regulatory agency of the Federal or a state government or listed in the U.S. Pharmacopoeia or other generally recognized pharmacopoeia for use in animals, and more particularly in humans. 
         [0230]    The term “excipient” refers to a diluent, adjuvant, carrier, or vehicle with which the compound is administered. Such pharmaceutical carriers can be sterile liquids, such as water and oils, including those of petroleum, animal, vegetable or synthetic origin, such as peanut oil, soybean oil, mineral oil, sesame oil and the like. Water or aqueous solution saline solutions and aqueous dextrose and glycerol solutions are preferably employed as carriers, particularly for injectable solutions. Suitable pharmaceutical carriers are described in “Remington&#39;s Pharmaceutical Sciences” by E. W. Martin. 
         [0231]    The term “adjuvant” refers to a compound or mixture that enhances the immune response to an antigen. An adjuvant can serve as a tissue depot that slowly releases the antigen and also as a lymphoid system activator that non-specifically enhances the immune response. Often, a primary challenge with an antigen alone, in the absence of an adjuvant, will fail to elicit a humoral or cellular immune response. Adjuvants include, but are not limited to, complete Freund&#39;s adjuvant, incomplete Freund&#39;s adjuvant, saponin, mineral gels such as aluminum hydroxide, surface active substances such as lysolecithin, pluronic polyols, polyanions, peptides, oil or hydrocarbon emulsions, keyhole limpet hemocyanins, dinitrophenol, and potentially useful human adjuvants such as BCG (bacille Calmette-Guerin) and Corynebacterium parvmm. Preferably, the adjuvant is pharmaceutically acceptable. 
       Cells 
       [0232]    The nucleotides of the present invention may be used to provide a method for identifying additional cell lines that are permissive for infection with HCV, comprising contacting (e.g. transfecting) a cell line in tissue culture with an infectious amount of HCV RNA of the present invention, e.g., as produced from the plasmid clones, and detecting replication and formation and release of viral particles of HCV in cells of the cell line. 
         [0233]    Naturally, the invention also extends to a method for identifying an animal that is permissive for infection with HCV, comprising introducing an infectious amount of the HCV RNA, e.g., as produced by the plasmids, to the animal, and detecting replication and formation and release of viral particles of HCV in the animal. By providing infectious HCV, e.g. comprising a dominant selectable marker, the invention further provides a method for selecting for HCV with further adaptive mutations that permit higher levels of HCV replication in a permissive cell line or animal comprising contacting (e.g. transfecting) a cell line in culture, or introducing into an animal, an infectious amount of the HCV RNA, and detecting progressively increasing levels of HCV RNA and infectious HCV viral particles in the cell line or the animal. 
         [0234]    In a specific embodiment, the adaptive mutation permits modification of HCV tropism. An immediate implication of this aspect of the invention is creation of new valid cell culture and animal models for HCV infection. 
         [0235]    The permissive cell lines or animals that are identified using the nucleic acids of the invention are very useful, inter alia, for studying the natural history of HCV infection, isolating functional components of HCV, and for sensitive, fast diagnostic applications, in addition to producing authentic HCV virus or components thereof. 
         [0236]    Because the HCV DNA, e.g., plasmid vectors, of the invention encode HCV components, expression of such vectors in a host cell line transfected, transformed, or transduced with the HCV DNA can be effected. 
         [0237]    For example, a baculovirus or plant expression system can be used to express HCV virus particles or components thereof. Thus, a host cell line may be selected from the group consisting of a bacterial cell, a yeast cell, a plant cell, an insect cell, and a mammalian cell. 
         [0238]    In one embodiment, the cell is a hepatocyte, or in another embodiment, the cell is the Huh-7 hepatoma cell line or a derived cell line such as Huh7.5, Huh7.5.1 cell line. 
         [0239]    In one embodiment, the cell, or in another embodiment, cell systems of this invention comprise primary cultures or other, also non-hepatic cell lines. “Primary cultures” refers, in one embodiment, to a culture of cells that is directly derived from cells or tissues from an individual, as well as cells derived by passage from these cells, or immortalized cells. 
         [0240]    In one embodiment, “cell line” refers to a population of cells capable of continuous or prolonged growth and division in vitro. The term “cell lines” also includes immortalized cells. Often, cell lines are clonal populations derived from a single progenitor cell. Such cell lines are also termed “cell clones”. It is further known in the art that spontaneous or induced changes can occur in karyotype during storage or transfer of such clonal populations. Therefore, cells derived from the cell clones referred to may not be precisely identical to the ancestral cells or cultures. According to the present invention, such cell clones may be capable of supporting replication of a vector, virus, viral particle, etc., of this invention, without a significant decrease in their growth properties, and are to be considered as part of this invention. 
         [0241]    It is to be understood that any cell of any organism that is susceptible to infection by or propagation of an HCV construct, virus or viral particle of this invention is to be considered as part of this invention, and may be used in any method of this invention, such as for screening or other assays, as described herein. 
         [0242]    Also, a method for in vitro producing a hepatitis C virus-infected cell comprising culturing the cell which produces virus particles of the present invention and infecting other cells with the produced virus particle in the culture. 
         [0243]    Naturally, the invention extends to any cell obtainable by such methods, for example any in vitro cell line infected with HCV, wherein the HCV has a genomic RNA sequence as described herein, such as a hepatitis C virus infected cell obtainable by any of the methods described. 
         [0244]    In one embodiment, the cell line is a hepatocyte cell line such as Huh7 or derived cell lines e.g. Huh7.5 or Huh7.5.1. 
         [0245]    Thus in one embodiment the present invention relates to a cassette vector for cloning viral genomes inserted therein the nucleic acid of the invention and having an active promoter upstream thereof. 
         [0246]    An embodiment is a method for producing a cell which replicates strains from the group consisting of H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,AFIVR1  (1b/2a), J6/JFH 1 ΔHVR1  (2a/2a), J8/JFH1 ΔHVR1  (2b/2a), S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), ED43/JFH1 A2819G,A3269T,ΔHVR1  (4a/2a), SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a), HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) and QC69/JFH1 ΔHVR1  (7a/2a) comprising introducing the RNAs of the invention into a cell. 
         [0247]    In an embodiment this cell is Huh7.5. 
         [0248]    An embodiment is the cell obtainable by the method for producing a cell which replicates strains from the group consisting of H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J6/JFH1 ΔHVR1  (2a/2a), J8/JFH1 ΔHVR1  (2b/2a), S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), ED43/JFH1 A2819G,A3269T,ΔHVR1  (4a/2a), SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a), HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) and QC69/JFH1 ΔHVR1  (7a/2a) comprising introducing the RNAs of the invention into a cell. 
         [0249]    In a further embodiment the present invention relates to a method for producing a cell, which replicates H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), 14/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J6/JFH1 ΔHVR1  (2a/2a), J8/JFH1 ΔHVR1  (2b/2a), S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), ED43/JFH1 A2819G,A3269T,ΔHVR1  (4a/2a), SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a), HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) or QC69/JFH1 ΔHVR1  (7a/2a) and produces a virus particle comprising introducing a nucleic acid molecule into a cell, wherein said nucleic acid molecule comprises at least 90% identity to that of SEQ ID NO 7, 8, 9, 10, 11, 12, 19 or 20. 
         [0250]    In a further embodiment the present invention relates to a method for producing a cell, which replicates HCV H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J6/JFH1 ΔHVR1  (2a/2a), J8/JFH1 ΔHVR1  (2b/2a), S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), ED43/JFH1 A2819G,A3269T,ΔHVR1  (4a/2a), SA13/JFH1 C3408G,A3696G,ΔHVR1  (5a/2a), HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) or QC69/JFH1 ΔHVR1  (7a/2a) and produces a virus particle comprising introducing an amino acid molecule into a cell, wherein said amino acid molecule comprises at least 90% identity to that of SEQ ID NO 1, 2, 3, 4, 5, 6, 22 or 23. 
         [0251]    In a further embodiment the present invention relates to a method for producing a cell, which replicates H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J8/JFH1 ΔHVR1  (2b/2a) or S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a) and produces a virus particle comprising 
         [0000]    (i) introducing a nucleic acid molecule into a cell, wherein said nucleic acid molecule comprises at least 90% identity to that of SEQ ID NO 7, 19, 20 or 9 which
 
(ii) at least one adaptive mutation in the nucleic acid sequence of E1 or E2.
 
         [0252]    In a further embodiment the present invention relates to a method for producing a cell, which replicates HCV H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J8/JFH1 ΔHVR1  (2b/2a) or S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a) and produces a virus particle comprising 
         [0000]    (i) introducing an amino acid molecule into a cell, wherein said amino acid molecule comprises at least 90% identity to that of SEQ ID NO 1, 22, 23 or 3 which
 
(ii) at least one adaptive mutation in the nucleic acid sequence of E1 or E2.
 
         [0253]    In another embodiment the present invention relates to a method for producing a cell, which replicates HCV H77/JFH1 T2700c,A4080T,ΔHVR1  (1a/2a) and produces a virus particle comprising: 
         [0000]    (i) introducing a nucleic acid molecule into a cell, wherein said nucleic acid molecule comprises at least 90% identity to that of SEQ ID NO 7, which
 
(ii) at least one adaptive mutation in the nucleic acid sequence of E1 or E2 selected from the group consisting of A1122G, A1671G, A1766G and C2538T.
 
         [0254]    In another embodiment the present invention relates to a method for producing a cell, which replicates HCV H77/JFH1 T2700c,A4080T,ΔHVR1  (1a/2a) and produces a virus particle comprising: 
         [0000]    (i) introducing a nucleic acid molecule into a cell, wherein said nucleic acid molecule comprises at least 90% identity to that of SEQ ID NO 7, which
 
(ii) at least one adaptive mutation in the nucleic acid sequence of E1 or E2 selected from the group consisting of T1383G, T1421C, A1628G and T2385A.
 
         [0255]    In another embodiment the present invention relates to a method for producing a cell, which replicates HCV J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a) and produces a virus particle comprising: 
         [0000]    (i) introducing a nucleic acid molecule into a cell, wherein said nucleic acid molecule comprises at least 90% identity to that of SEQ ID NO 19, which
 
(ii) at least one adaptive mutation in the nucleic acid sequence of E1 or E2 selected from the group consisting of A1236G, C1428T, A1643C, A2066G, G2225A and G2468C.
 
         [0256]    In another embodiment the present invention relates to a method for producing a cell, which replicates HCV J8/JFH1 ΔHVR1  (2b/2a) and produces a virus particle comprising: 
         [0000]    (i) introducing a nucleic acid molecule into a cell, wherein said nucleic acid molecule comprises at least 90% identity to that of SEQ ID NO 20, which
 
(ii) at least one adaptive mutation in the nucleic acid sequence of E1 or E2 selected from the group consisting of T1574A.
 
         [0257]    In another embodiment the present invention relates to a method for producing a cell, which replicates HCV J8/JFH1 ΔHVR1  (2b/2a) and produces a virus particle comprising: 
         [0000]    (i) introducing a nucleic acid molecule into a cell, wherein said nucleic acid molecule comprises at least 90% identity to that of SEQ ID NO 20, which
 
(ii) at least one adaptive mutation in the nucleic acid sequence of E1 or E2 selected from the group consisting of C1571G, T1572G, A1580G, A1652T and A1941C.
 
         [0258]    In another embodiment the present invention relates to a method for producing a cell, which replicates HCV S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a) and produces a virus particle comprising: 
         [0000]    (i) introducing a nucleic acid molecule into a cell, wherein said nucleic acid molecule comprises at least 90% identity to that of SEQ ID NO 9, which
 
(ii) at least one adaptive mutation in the nucleic acid sequence of E1 or E2 selected from the group consisting of C1446T.
 
         [0259]    In another embodiment the cell is any cell expressing the genes necessary for HCV infection and replication, such as but not limited to CD81, SR-BI, Claudin-1, -4, -6 or -9 and the low-density lipoprotein receptor. 
         [0260]    The invention further provides various methods for producing HCV virus particles, including by isolating HCV virus particles from the HCV-infected non-human animal of invention; culturing a cell line of the invention under conditions that permit HCV replication and virus particle formation; or culturing a host expression cell line transfected with HCV DNA under conditions that permit expression of HCV particle proteins; and isolating HCV particles or particle proteins from the cell culture. The present invention extends to an HCV virus particle comprising a replication-competent HCV genome RNA, or a replication-defective HCV genome RNA, corresponding to an HCV nucleic acid of the invention as well. 
       Virus Particles 
       [0261]    The production of authentic virus proteins (antigens) may be used for the development and/or evaluation of diagnostics. The cell culture system according to the invention also allows the expression of HCV antigens in cell cultures. In principle these antigens can be used as the basis for diagnostic detection methods. 
         [0262]    The production of HCV viruses and virus-like particles, in particular for the development or production of therapeutics and vaccines as well as for diagnostic purposes is an embodiment of the present invention. Especially cell culture adapted complete HCV genomes, which could be produced by using the cell culture system according to the invention, are able to replicate and form viral particles in cell culture with high efficiency. These genomes have the complete functions of HCV and in consequence they are able to produce infectious viruses. 
         [0263]    Thus in one embodiment the present invention relates to a method for producing a hepatitis C virus particle of the present invention or parts thereof, comprising culturing a cell or an animal to allow either to produce the virus. 
         [0264]    In another embodiment the inventions provides a hepatitis C virus particle obtainable by the method described. 
         [0265]    Because the invention provides, inter alia, infectious HCV RNA, the invention provides a method for infecting an animal with HCV which comprises administering an infectious dose of HCV RNA, such as the HCV RNA transcribed from the plasmids described above, to the animal. Naturally, the invention provides a non-human animal infected with HCV of the invention, which non-human animal can be prepared by the foregoing methods. 
         [0266]    A further advantage of the present invention is that, by providing a complete functional HCV genome, authentic HCV viral particles or components thereof, which may be produced with native HCV proteins or RNA in a way that is not possible in subunit expression systems, can be prepared. 
         [0267]    In addition, since each component of HCV of the invention is functional (thus yielding the authentic HCV), any specific HCV component is an authentic component, i.e., lacking any errors that may, at least in part, affect the clones of the prior art. Indeed, a further advantage of the invention is the ability to generate HCV virus particles or virus particle proteins that are structurally identical to or closely related to natural HCV virions or proteins. Thus, in a further embodiment, the invention provides a method for propagating HCV in vitro comprising culturing a cell line contacted with an infectious amount of HCV RNA of the invention, e.g., HCV RNA translated from the plasmids described above, under conditions that permit replication of the HCV RNA. 
         [0268]    Thus, an embodiment of the invention refers to a method for in vitro producing a hepatitis C virus-infected cell comprising culturing a cell which replicates strains from the group consisting of H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J6/JFH1 ΔHVR1  (2a/2a), J8/JFH1 ΔHVR1  (2b/2a), S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), ED43/JFH1 A2819G,A3269T,ΔHVR1  (4a/2a), SA13/JFH1 C3408G,A3696G,ΔHVR1  (5a/2a), HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) and QC69/JFH1 ΔHVR1 ( 7a/2a) comprising introducing the RNAs of the invention into a cell, and infecting other cells with the produced virus particle in the culture. 
         [0269]    A hepatitis C virus infected cell obtainable by the method described is an embodiment of the invention. 
         [0270]    Further the viability of the developed viruses may be determined in vivo, either in SCID-uPA mice engrafted with human liver tissue or in chimpanzees as shown in Lindenbach et al. 2006. 
         [0271]    In one embodiment, the method further comprises isolating infectious HCV. In another embodiment, the method further comprises freezing aliquots of said infectious HCV. According to this aspect of the invention, and in one embodiment, the HCV is infectious following thawing of said aliquots, and in another embodiment, the HCV is infectious following repeated freeze-thaw cycles of said aliquots. 
         [0272]    Screening for anti-viral drugs and the determination of drug resistance 
         [0273]    It can be assumed that resistance to therapy occurs due to the high mutation rate of the HCV genome. This resistance, which is very important for the clinical approval of a substance, can be detected with the cell culture system according to the invention. Cell lines, in which the HCV-RNA construct or the HCV genome or subgenome replicates and produces infectious viral particles, are incubated with increasing concentrations of the relevant substance and the replication of the viral RNA is either determined by means of an introduced reporter gene or through the qualitative or quantitative detection of the viral nucleic acids or proteins. The release of viral particles is determined by measuring HCV RNA and infectivity titers in the cell culture supernatant. Resistance is given if no, or a reduced inhibition of the replication and release of viral particles, can be observed with the normal concentration of the active substance. The nucleotide and amino acid replacements responsible for the therapy resistance can be determined by recloning the HCV-RNA (for example by the means of RT-PCR) and sequence analysis. By cloning the relevant replacement(s) into the original construct its causality for the resistance to therapy can be proven. 
         [0274]    While the replicon systems facilitated testing of drugs interfering with replication such as NS3/4A protease and polymerase inhibitors, the variant genomes obtained in the present study may prove useful for different research topics. 
         [0275]    The systems developed in this invention are ideal candidates for specific testing of therapeutics in general and therapeutics targeting viral entry in particular. The genomes can be valuable for testing antibodies and other drugs acting on entry level, such as fusion inhibitors. 
         [0276]    The present inventors conducted cross-genotype neutralization studies in HCV cell culture systems recapitulating the entire viral life cycle using JFH1-based viruses with envelope sequences of all 7 major genotypes, and important subtypes 1b and 2b, which has previously not been possible. HCV E1/E2 assembled on HCV pseudo particles (HCVpp), used in previous neutralization studies could show an unphysiological confirmation, glycosylation pattern and/or lipoprotein association due to the nature of the HCVpp as well as the non-hepatic producer cell-lines used in such experiments. 
         [0277]    In such studies the viral particles are incubated with the neutralizing substance, e.g. patient derived antibodies present in serum, prior to incubation with cells permissive and susceptible to viral infection. The neutralizing effect, i.e. the inhibitory effect on viral entry, is measured e.g. by relating the number of focus forming units (FFUs, defined as foci of adjacent infected cells) to the equivalent count in a control experiment done under same circumstances without the active inhibitor molecule. 
         [0278]    The inventors of the present invention showed that JFH1-based viruses of the genotype 1a, 1b, 2b, 4a, 5a, 6a and 7a were efficiently neutralized by chronic phase H06 genotype 1a serum derived from reference Patient H. The results in the cell culture systems compare well to neutralization experiments using Patient H serum from year 26 (H03) carried out in HCVpp systems with envelope proteins of the same prototype isolates of all 6 HCV genotypes as used in the present application, and heterogeneity between the genotypes is thus as previously reported by Meunier et al. 2005. 
         [0279]    In addition the present inventors found that cross-genotype neutralization extended to a chronic phase genotype 4a serum (AA), which efficiently neutralized genotype 2b, 4a, 5a, 6a and 7a. Also, the cross-genotype neutralization extended to a chronic phase genotype 5a serum (SA3), which efficiently neutralized genotype 2b, 4a, 5a, 6a and 7a. Accordingly, the JFH1-based cell culture systems which have been developed for HCV genotype 1a, 1b, 2a, 2b, 3a, 4a, 5a, 6a and 7a provide a valuable tool for efficiently screening for and identifying new candidate HCV genotype 1a, 1b, 2a, 2b, 3a, 4a, 5a, 6a and 7a inhibitors e.g. of entry e.g. in serum derived from infected patients. Accordingly this invention, allows identification and raise of cross-neutralizing antibodies, which is important for the development of active and passive immunization strategies. Furthermore the availability of cell culture grown HCV particles bearing envelope proteins of the seven major genotypes and important subtypes enables the development of inactivated whole virus vaccines and comprehensive virus neutralization studies. The development of infectious viruses without HVR1 facilitates the development of inhibitors and antibodies specifically aimed at other, less variable targets on the surface of the virus particle. 
         [0280]    It has been demonstrated that infectious particles without HVR1 possess a uniform density around 1.1 g/ml (Example 6), unlike that seen for the wt viruses where infectious particle densities are found in a range of 1.0 to 1.1 g/ml. This difference is interesting, especially in conjunction with the neutralization data showing marked improvement in neutralization of the HVR1 deleted viruses when compared to their respective wt counterpart (Example 5). These neutralization data show complete neutralization of all HVR1 deleted viruses at high dilutions of the patient sera. In the case of wt viruses the neutralization effect is much more varied, ranging from no neutralization (AA and SA3 serum against J6/JFH ΔHVR1 ,), to neutralization reaching a plateau beyond which further neutralization seems unattainable (H06 serum against J6/JFH ΔHVR1  and S52/JFH1 T2718G,T7160C,ΔHVR1 ), to going toward full neutralization spread out over an extended serum dilution interval (H06 serum against H77/JFH1 T2700C,A4080T,ΔHVR1 , SA13/JFH1 C3405G,A3696G,ΔHVR1 , and HK6a/JFH1 T1389C,ΔHVR1 ). 
         [0281]    Taken together, this shows that wt viruses are found greatly associated to a low density moiety, the candidate being lipoproteins of low density, and that this association appears to have a shielding effect on, otherwise, readily available neutralization epitopes. It has also been shown that H77/JFH1 T2700C,A4080T,ΔHVR1  displays HVR1 on its surface and that antibodies raised against this region will neutralize the virus (Example 5). It would therefore stand to reason that one would need neutralizing antibodies against both HVR1 and other epitopes to attain a complete neutralization against all types of HCV virus particles. Testing of these mixed products would depend on viruses with and without HVR1, like the ones the present inventors have generated for this invention. 
         [0282]    One might draw into question the clinical importance of non-naturally occurring, HVR1 truncated viruses. Although this issue is a complex one there are several factors suggesting that the study of these viruses yields data of clinical importance. Firstly, H77 with HVR1 truncation has been shown to spread, albeit attenuated, in two chimpanzees (Forms et al, 2000). Secondly, chronic patient serum often contains high titers of non-HVR1 antibodies capable of neutralizing the HVR1 truncated viruses without this leading to viral clearance. 
         [0283]    In one embodiment the present invention relates to a method for identifying neutralizing antibodies. 
         [0284]    In another one embodiment the present invention relates to a method for identifying cross-genotype neutralizing antibodies. 
         [0285]    In one embodiment the present invention relates to a method of raising neutralizing antibodies. 
         [0286]    In another embodiment the present invention relates to a method of raising cross-neutralizing antibodies. 
         [0287]    In one embodiment the present invention related to a method for screening new HCV genotype 1a, 1b, 2a, 2b, 3a, 4a, 5a, 6a and/or 7a inhibitors or neutralizing antibodies, comprising
       a) culturing at least one selected from the group consisting of a cell according to the present invention, a hepatitis C virus infected cell according to the present invention and a hepatitis C virus particle obtainable by the present invention together with a hepatitis C virus permissive cell, and   b) subjecting said virus or virus infected cell culture to a blood sample or derivatives thereof from a HCV genotype 1a, 1b, 2a, 2b, 3a, 4a, 5a, 6a and/or 7a infected patient   c) detecting the amount of replicating RNA and/or the virus particles.       
 
         [0291]    Thus, one embodiment of the present invention relates to a method for screening an anti-hepatitis C virus substance, comprising
       a) culturing at least one selected from the group consisting of a cell according to the present invention, a hepatitis C virus infected cell according to the present invention and a hepatitis C virus particle obtainable by the present invention together with a hepatitis C virus permissive cell,   b) subjecting said virus or virus infected cell culture to the anti-hepatitis C virus substance, and   c) detecting the replicating RNA and/or the virus particles in the resulting culture.       
 
         [0295]    In another embodiment, the inhibition of HCV replication and/or infection and/or pathogenesis includes inhibition of downstream effects of HCV. In one embodiment, downstream effects include neoplastic disease, including, in one embodiment, the development of hepatocellular carcinoma. 
         [0296]    In one embodiment, the invention provides a method of screening for anti-HCV therapeutics, the method comprising contacting a cell with an isolated nucleic acid molecule encoding an infectious recombinant HCV genome, comprising a chimeric HCV genome and contacting the cell with a candidate molecule, independently contacting the cell with a placebo and determining the effects of the candidate molecule on HCV infection, replication, or cell-to-cell spread, versus the effects of the placebo, wherein a decrease in the level of HCV infection, replication, or cell-to-cell spread indicates the candidate molecule is an anti-HCV therapeutic. 
         [0297]    In one embodiment, the method may be conducted be in vitro or in vivo. In one embodiment, the cells as described may be in an animal model, or a human subject, entered in a clinical trial to evaluate the efficacy of a candidate molecule. In one embodiment, the molecule is labelled for easier detection, including radio-labelled, antibody labelled for fluorescently labelled molecules, which may be detected by any means well known to one skilled in the art. 
         [0298]    In one embodiment, the candidate molecule is an antibody. 
         [0299]    In one embodiment, the term “antibody” refers to intact molecules as well as functional fragments thereof, such as Fab, F(ab′)2, and Fv. In one embodiment, the term “Fab” refers to a fragment, which contains a monovalent antigen-binding fragment of an antibody molecule, and in one embodiment, can be produced by digestion of whole antibody with the enzyme papain to yield an intact light chain and a portion of one heavy chain, or in another embodiment can be obtained by treating whole antibody with pepsin, followed by reduction, to yield an intact light chain and a portion of the heavy chain. In one embodiment, the term “F(ab′)2”, refers to the fragment of the antibody that can be obtained by treating whole antibody with the enzyme pepsin without subsequent reduction, F(ab′)2 is a dimer of two Fab′ fragments held together by two disulfide bonds. In another embodiment, the term “Fv” refers to a genetically engineered fragment containing the variable region of the light chain and the variable region of the heavy chain expressed as two chains, and in another embodiment, the term “single chain antibody” or “SCA” refers to a genetically engineered molecule containing the variable region of the light chain and the variable region of the heavy chain, linked by a suitable polypeptide linker as a genetically fused single chain molecule. 
         [0300]    Methods of producing these fragments are known in the art. 
         [0301]    In another embodiment, the candidate molecule is a small molecule. In one embodiment, the phrase “small molecule” refers to, inter-alia, synthetic organic structures typical of pharmaceuticals, peptides, nucleic acids, peptide nucleic acids, carbohydrates, lipids, and others, as will be appreciated by one skilled in the art. In another embodiment, small molecules, may refer to chemically synthesized peptidomimetics of the 6-mer to 9-mer peptides of the invention. 
         [0302]    In another embodiment, the candidate molecule is a nucleic acid. Numerous nucleic acid molecules can be envisioned for use in such applications, including antisense, siRNA, ribozymes, etc., as will be appreciated by one skilled in the art. 
         [0303]    It is to be understood that the candidate molecule identified and/or evaluated by the methods of this invention, may be any compound, including, inter-alia, a crystal, protein, peptide or nucleic acid, and may comprise an HCV viral product or derivative thereof, of a cellular product or derivative thereof. The candidate molecule in other embodiments, may be isolated, generated synthetically, obtained via translation of sequences subjected to any mutagenesis technique, or obtained via protein evolution techniques, well known to those skilled in the art, each of which represents an embodiment of this invention, and may be used in the methods of this invention, as well. 
         [0304]    In one embodiment, the compound identified in the screening methods as described, may be identified by computer modeling techniques, and others, as described herein. Verification of the activity of these compounds may be accomplished by the methods described herein, where, in one embodiment, the test compound demonstrably affects HCV infection, replication and/or pathogenesis in an assay, as described. In one embodiment, the assay is a cell-based assay, which, in one embodiment, makes use of primary isolates, or in another embodiment, cell lines, etc. In one embodiment, the cell is within a homogenate, or in another embodiment, a tissue slice, or in another embodiment, an organ culture. In one embodiment, the cell or tissue is hepatic in origin, or is a derivative thereof. In another embodiment, the cell is a commonly used mammalian cell line, which has been engineered to express key molecules known to be, or in another embodiment, thought to be involved in HCV infection, replication and/or pathogenesis. 
         [0305]    In another embodiment, protein, or in another embodiment, peptide or in another embodiment, other inhibitors of the present invention cause inhibition of infection, replication, or pathogenesis of HCV in vitro or, in another embodiment, in vivo when introduced into a host cell containing the virus, and may exhibit, in another embodiment, an IC50 in the range of from about 0.0001 nM to 100 μM in an in vitro assay for at least one step in infection, replication, or pathogenesis of HCV, more preferably from about 0.0001 nM to 75 μM, more preferably from about 0.0001 nM to 50 μM, more preferably from about 0.0001 nM to 25 μM, more preferably from about 0.0001 nM to 10 μM, and even more preferably from about 0.0001 nM to 1 μM. 
         [0306]    In another embodiment, the inhibitors of HCV infection, or in another embodiment, replication, or in another embodiment, pathogenesis, may be used, in another embodiment, in ex vivo scenarios, such as, for example, in routine treatment of blood products wherein a possibility of HCV infection exists, when serology indicates a lack of HCV infection. 
         [0307]    In another embodiment, the anti-HCV therapeutic compounds identified via any of the methods of the present invention can be further characterized using secondary screens in cell cultures and/or susceptible animal models. In one embodiment, a small animal model may be used, such as, for example, a tree shrew Tupaia belangeri chinensis. In another embodiment, an animal model may make use of a chimpanzee. Test animals may be treated with the candidate compounds that produced the strongest inhibitory effects in any of the assays/methods of this invention. In another embodiment, the animal models provide a platform for pharmacokinetic and toxicology studies. 
       Vaccines 
       [0308]    The construct according to the invention by itself can also be used for various purposes in all its embodiments. This includes the construction of hepatitis C viruses or HCV-like particles and their production in cell cultures as described. 
         [0309]    These HCV or HCV-like particles can be used in particular as vaccine. Thus, one embodiment of the present invention relates to a hepatitis C vaccine comprising a hepatitis C virus particle according to the invention or a part thereof. 
         [0310]    In another embodiment, the nucleic acids, vectors, viruses, or viral particles may be further engineered to express a heterologous protein, which, in another embodiment, is mammalian or a derivative thereof, which is useful in combating HCV infection or disease progression. Such proteins may comprise cytokines, growth factors, tumor suppressors, or in one embodiment, may following infection, be expressed predominantly or exclusively on an infected cell surface. According to this aspect of the invention, and in one embodiment, such molecules may include costimulatory molecules, which may serve to enhance immune response to infected cells, or preneoplastic cells, or neoplastic cells, which may have become preneoplastic or neoplastic as a result of HCV infection. In one embodiment, the heterologous sequence encoded in the nucleic acids, vectors, viruses, or viral particles of this invention may be involved in enhanced uptake of a nucleic acids, vectors, viruses, or viral particles, and may specifically target receptors thought to mediate HCV infection. 
         [0311]    Thus, one embodiment of the invention relates to a hepatitis C vaccine comprising a hepatitis C virus particle from a cell which replicates strains from the group consisting of H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J6/JFH1 ΔHVR1  (2a/2a), J8/JFH1 ΔHVR1  (2b/2a), S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a), ED43/JFH1 A2819G,A3269T,ΔHVR1  (4a/2a), SA13/JFH1 C3405G,A3696G,ΔHVR1  (5a/2a), HK6a/JFH1 T1389C,A1590G,ΔHVR1  (6a/2a) and QC69/JFH1 ΔHVR1  (7a/2a) comprising introducing the RNA of the invention. 
         [0312]    An embodiment relates to an antibody against the hepatitis C virus particle described above. 
         [0313]    Further, the present invention relates to a method for producing a hepatitis C virus vaccine comprising using a hepatitis C virus particle according to the invention or part thereof as an antigen, and naturally any antibody against such hepatitis C virus particle. 
         [0314]    Using the HVR1 deleted constructs one could recombinantly express HVR1 deleted E2 protein. This protein could be used for the generation of specific antibodies that might serve in passive immunization. In addition the recombinantly expressed protein could be used in vaccine development. This vaccine development would also allow for non-HVR1 specific effects and the recombinant protein lacking HVR1 does therefore offer many of the same possibilities as the HVR1 deleted HCV virus particle itself. 
         [0315]    Use of the HVR1 viruses for diagnostic/prognostic purposes 
         [0316]    The developed viruses could be applied as prognostic tool in infected patient and could thus contribute to individualized patient treatment. The availability of genotype specific virus with and without HVR1 may allow for the development of a prognostic assay where the antibody response of the patient was tested against the relevant genotype virus with and without HVR1 to ascertain whether the antibodies raised by the patient will have a lasting effect. This is possible due to the broadly neutralizing effect of antibodies in patient sera raised against HCV. 
       Kits 
       [0317]    In a related aspect, the invention also provides a test kit for HCV comprising HCV virus components, and a diagnostic test kit for HCV comprising components derived from an HCV virus as described herein. 
         [0318]    Furthermore the invention also provide test kits, for screening for new HCV genotype 1a, 1b, 2a, 2b, 3a, 5a, 6a and 7a inhibitors, neutralizing and cross neutralizing antibodies, comprising HCV virus components. 
       General 
       [0319]    Reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in any country. 
         [0320]    All patent and non-patent references cited in the present application, are hereby incorporated by reference in their entirety. 
         [0321]    As will be apparent, preferred features and characteristics of one aspect of the invention may be applicable to other aspects of the invention. The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting on the invention described herein. Scope of the invention is thus indicated be the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced by reference therein. 
         [0322]    Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. 
         [0323]    In addition, singular reference do not exclude a plurality. Thus, references to “a”, “an”, “first”, “second” etc. do not preclude a plurality. 
         [0324]    The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting on the invention described herein. Scope of the invention is thus indicated be the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced by reference therein. 
         [0325]    The invention will hereinafter be described by way of the following non-limiting Figures and Examples. 
         [0326]    It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention. 
         [0327]    All patent and non-patent references cited in the present application, are hereby incorporated by reference in their entirety. 
         [0328]    The invention will now be described in further details in the following non-limiting examples. 
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 Sequence listing 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 SEQ ID NO 1 
                 H77/JFH1 V787A, Q1247L, ΔHVR1  (1a/2a) - Amino Acid  
               
               
                   
                 Sequence 
               
               
                 SEQ ID NO 2  
                 J6/JFH1 ΔHVR1  (2a/2a) - Amino Acid Sequence 
               
               
                 SEQ ID NO 3  
                 S52/JFH1 I793S, S2274P, ΔHVR1  (3a/2a) - Amino Acid  
               
               
                   
                 Sequence 
               
               
                 SEQ ID NO 4  
                 ED43/JFH1 T827A, T977S, ΔHVR1  (4a/2a) - Amino Acid  
               
               
                   
                 Sequence 
               
               
                 SEQ ID NO 5  
                 SA13/JFH1 A1022G, K1119R, ΔHVR1  (5a/2a) - Amino Acid  
               
               
                   
                 Sequence 
               
               
                 SEQ ID NO 6 
                 HK6a/JFH1 F350S, N417T, ΔHVR1  (6a/2a) - Amino Acid  
               
               
                   
                 Sequence 
               
               
                 SEQ ID NO 7 
                 H77/JFH1 T2700C, A4080T, ΔHVR1  (1a/2a) - DNA 
               
               
                 SEQ ID NO 8 
                 J6/JFH1 ΔHVR1  (2a/2a) - DNA 
               
               
                 SEQ ID NO 9 
                 S52/JFH1 T2718G, T7160C, ΔHVR1  (3a/2a) - DNA 
               
               
                 SEQ ID NO 10 
                 ED43/JFH1 A2819G, A3269T, ΔHVR1  (4a/2a) - DNA 
               
               
                 SEQ ID NO 11 
                 SA13/JFH1 C3405G, A3696G, ΔHVR1  (5a/2a) - DNA 
               
               
                 SEQ ID NO 12 
                 HK6a/JFH1 T1389C, A1590G, ΔHVR1  (6a/2a) - DNA 
               
               
                 SEQ ID NO 13 
                 H77/JFH1 (H261R, Q444R), V787A, Q1247L, ΔHVR1  (1a/2a) -  
               
               
                   
                 Amino Acid Sequence 
               
               
                 SEQ ID NO 14 
                 H77/JFH1 (N476D, S733F), V787A, Q1247L, ΔHVR1  (1a/2a) -  
               
               
                   
                 Amino Acid Sequence 
               
               
                 SEQ ID NO 15 
                 S52/JFH1 (A369V), I793S, S2274P, ΔHVR1  (3a/2a) - Amino Acid  
               
               
                   
                 Sequence 
               
               
                 SEQ ID NO 16 
                 H77/JFH1 (A1122G, A1671G), T2700C, A4080T, ΔHVR1  (1a/2a) -  
               
               
                   
                 DNA 
               
               
                 SEQ ID NO 17 
                 H77/JFH1 (A1766G, C2538T), T2700C, A4080T, ΔHVR1  (1a/2a) -  
               
               
                   
                 DNA 
               
               
                 SEQ ID NO 18 
                 S52/JFH1 (C1446T), T2718G, T7160C, ΔHVR1  (3a/2a) - DNA 
               
               
                 SEQ ID NO 19 
                 J4/JFH1 T2996C, A4827T, ΔHVR1  (1b/2a) - DNA 
               
               
                 SEQ ID NO 20 
                 J8/JFH1 ΔHVR1  (2b/2a) - DNA 
               
               
                 SEQ ID NO 21 
                 J8/JFH1 (T1574A), ΔHVR1  (2b/2a) - DNA 
               
               
                 SEQ ID NO 22 
                 J4/JFH1 F886L, Q1496L, ΔHVR1  (1b/2a)- Amino Acid Sequence 
               
               
                 SEQ ID NO 23 
                 J8/JFH1 ΔHVR1  (2b/2a) - Amino Acid Sequence 
               
               
                 SEQ ID NO 24 
                 J8/JFH1 (Y412N), ΔHVR1  (2b/2a) - Amino Acid Sequence 
               
               
                   
               
             
          
         
       
     
       EXAMPLES 
     Materials and methods 
     Culturing, Transfection and Infection of Huh7.5 Cells 
       [0329]    Culturing of Huh7.5 The human hepatoma cell line Huh7.5 was cultured in Dulbecco&#39;s modified Eagle medium 4500 mg/L glucose GlutaMAX-I Pyruvate (Gibco/Invitrogen Corporation, Carlsbad, Calif.) containing 10% heat-inactivated fetal bovine serum (Sigma, St. Louis, Mo.), penicillin 100 U/mL and streptomycin 100 g/mL (Gibco/Invitrogen Corporation), at 5% CO2 and 37° C. Cells were split every second to third day at a ratio of 1:2 to 1:3. One day prior to transfection or infection, 4*10 5  cells/well were plated into 6-well plates (NUNC). In transfections, 2.5 μg HCV RNA derived from in vitro transcription was mixed with 5 μl of Lipofectamine 2000 (Invitrogen) and incubated in 500 μl OptiMEM (Invitrogen) for 20 min. The RNA-Lipofectamine 2000 complexes were then added to the 6-well plates and left to transfect cells at 37° C., 5% CO 2  for 16-24 h before washing with PBS. In infections, virus supernatants were added and left to infect for 16-24 h before washing with PBS. Collected cell culture supernatants were sterile filtered with a pore size of 0.45 μm (Nalgene) and stored at −80° C. Every time cells were split, a small amount of each culture was transferred to cover slides (NUNC) for evaluation of the percentage of infected cells by HCV antigen immunostaining (see below). Positive control virus for transfections of mutated virus was always the non-mutated virus. Negative control virus for transfections was always the replication deficient J6/JFH GND  (abbreviated: GND). 
       Evaluation of Infected Cell Cultures 
       [0330]    Viral spread in cell cultures was monitored by immunostaining of cells on cover slides for HCV Core or NS5A antigen with 1:200 dilution of mouse anti-HCV core protein monoclonal antibody (B2) (Anogen, Yes Biotech Laboratories) in PBS containing 5% BSA or 1:500 dilution of mouse anti-NS5A, 9E10 in PBS containing 5% BSA, respectively, followed by a 1:500 dilution of goat anti-mouse Alexa594 conjugated (H+L) secondary antibody (Invitrogen) in PBS/Tween. Cell nuclei were counterstained with Hoechst 33342 (Invitrogen). The percentage of HCV-positive cells was evaluated by fluorescence microscopy, assigning values of 0% (no cells infected), 1%, 5%, 10%-100% (in steps of 10%) cells infected. Supernatant infectivity titers were determined as 50% tissue culture infectious dose (TCID 50 )/mL or as focus forming units (FFU)/mL. In both assays, 6×103 Huh7.5 cells/well of poly-D-lysine coated 96 well plates (Nunc) were plated out the day before infection with 10-fold dilutions of virus containing supernatant. After 48 h incubation at 37° C., 5% CO 2 , HCV infected cells were visualized by immunostaining for HCV NS5A. NS5A antigen staining was performed as previously described using primary antibody anti-NS5A, 9E10 at 1:1000 in PBS/Tween, secondary antibody ECL anti-mouse immunoglobulin (Ig)G, horseradish-peroxidase-linked whole antibody (GE Healthcare Amersham, Buckinghamshire,UK) at 1:300 in PBS/Tween, and horseradish-peroxidase substrate (DAB substrate kit, DAKO, Glostrup, Denmark). HCV infected cells were detected by light microscopy. In transfections FFU/mL calculations were based on counting FFU of wells with 5-100 FFU in three independent virus dilutions with one replicate each and in kinetic experiments calculations were based on taking average of triplicates by counting FFU of wells with 5-100 FFU. TCID 50 /ml calculations were done using the standard Reed-Munch limiting dilution formula for six replicates. 
       Real-Time PCR (TaqMan) Quantification of HCV RNA 
       [0331]    Supernatant HCV RNA titers were measured by a 5′ UTR based Real Time RT-PCR. RNA was purified from 200 μL of heat inactivated (56° C. for 30 min) cell culture supernatant and eluted in a final volume of 50 μL using the Total Nucleic Acid Isolation Kit (Roche) in combination with the Total NA Variable Elution Volume protocol on a MagNA Pure LC Instrument (Roche). As an internal control, Phocine Distemper Virus (PDV) was added to the lysis buffer in a concentration titrated to yield a Ct of ˜32 upon real-time PCR analysis. In parallel to RNA purified from cell culture supernatants a quantitative HCV standard panel covering RNA concentrations of 0 to 5×10 6  IU/mL in one-log increments (OptiQuant HCV Panel, AcroMetrix) was analysed. Real-time PCR analyses of HCV and PDV RNA were carried out in two separate reactions using the TaqMan EZ RT-PCR Kit (Applied Biosystems). For HCV, primers and a FAM-labelled MGB-probe were directed against the 5′ UTR and were previously shown to perform equivalently against a panel of the six major HCV genotypes in a different TaqMan assay (Engle et al. 2008). For PDV, a ready-to-use primer/probe mix was used (Dr. H.G.M. Niesters, Department of Virology, Erasmus Medical Centre, Rotterdam, The Netherlands). The PCR analysis was performed on a 7500 Real-Time PCR System (Applied Biosystems) using 50° C. for 2 min, 60° C. for 30 min and 95° C. for 5 min followed by 45 cycles of 94° C. for 20 min and 62° C. for 1 min. HCV RNA titers (IU/ml) were calculated using a standard curve created from the known concentrations of the standard panel and their corresponding Ct values. The reproducible detection limit of the assay was 500 IU/ml. In order to confirm successful purification, amplification and the absence of PCR inhibitors, the Ct value of the PDV reaction was compared to the expected Ct value (based on a mean of all previous runs; n&gt;9) using the MedLab QC freeware programme. The results of samples with an actual Ct value within ±25D of the expected Ct value were accepted. 
       Sequencing of Cell Culture Derived HCV RNA 
       [0332]    HCV RNA was extracted using High Pure Viral Nucleic Acid Kit (Roche) and cDNA was generated using Superscript III (Invitrogen). RNA was degraded using RNase T and H (Ambion). Next, 1st and 2nd round PCR was carried out using BD Advantage II polymerase mix (Clontech) using specific primers (as described in the previous patent applications for H77/JFH1 T2700C,A4080T  (1a/2a), J4/JFH1 T2996C,A4827T (1b/2a), J8/JFH1 (2b/2a), S52/JFH1 T2718G,T7160C  (3a/2a), ED43/JFH1 A2819G,A3269T  (4a/2a), SA13/JFH1 C3405G,A3696G  (5a/2a), and HK6a/JFH1 T1389C,A1590G  (6a/2a)). The resulting 12 amplicons were directly sequenced using specific primers (As described in the previous patent applications for H77/JFH1 T2700C,A4080T  (1a/2a), J4/JFH1 T2996C,A4827T  (1b/2a), J8/JFH1 (2b/2a), S52/JFH1 T2718G,T7160C  (3a/2a), ED43/JFH1 A2819G,A3269T  (4a/2a), SA13/JFH1 C3405G,A3696G  (5a/2a) and HK6a/JFH1 T1389C,A1590G  (6a/2a)) and the sequence files were assembled and analyzed in Sequencher software version 4.7. All plasmids used in transfections were sequenced in the entire HCV coding sequence. 
       Cloning 
       [0333]    Deletions were carried out by fusion PCR using PFU polymerase (Stratagene) or Quikchange XL kit (Invitrogen) and the generation of point mutations was done using the Quikchange XL kit (Invitrogen). 
       In Vitro Transcription 
       [0334]    5 μg of plasmids were linearized using XbaI (New England Biolabs) and treated with mung bean nuclease (New England Biolabs) for 1 h to obtain the correct 3′ end of the HCV genome. The DNA was then purified using Qiaquick PCR purification kit (Qiagen) and subsequently used to generate HCV coding RNA by T7 polymerase in vitro transcription (Promega) for 2 h at 37° C. 
       Density Gradient Centrifugation 
       [0335]    Continuous gradients were made using Iodixanol, which has been shown to best preserve host-lipoprotein virus complexes. The gradient was generated by layering 2.5 ml each of 40%, 30%, 20% and 10% Optiprer 4  (Iodixanol, Axis-Shield) diluted with PBS from a 60% stock. The step gradients were then left upright for 24 h at 4° C. for the formation of semi-continuous gradients. To reduce sample volume and to concentrate infectious virus we used amicon centrifugation filters (Millipore), obtaining virus in a volume of ˜250 μl and loaded this on top of the gradient immediately prior to ultracentrifugation. This was carried out at 35000 RPM (151263×rcf) for 18 h at 4° C. using a Beckman SW-41 rotor mounted in a Beckman XL-70 ultracentrifuge. After centrifugation gradient fractions were harvested from the bottom into ˜550 μl fractions and 400 μl of these were weighed to calculate the fraction densities. Fractions were infectivity and HCV RNA titrated at a 1:10 dilution as we had tested and found that up to 10% Iodixanol had no significant effect on HCV infectivity and HCV RNA titers. 
       Neutralization of FICV cc  by Patient Sera 
       [0336]    100-400×TCID 50  of viruses were incubated for 1 h at 37° C. with either two-fold dilutions of heat-inactivated (56° C. for 30 min) patient serum or four-fold dilutions of polyclonal IgGs purified from serum. Huh7.5 cells were plated at 6×10 3 /well the day before the experiment in a poly-D-lysine-coated 96-well plate. The viruses were incubated with serum or IgG for 1 h at 37° C. and subsequently incubated with the cells for 3 h. Then cells were washed once with pre-warmed media and incubated in 200 μl of fresh medium for 48 h before NS5A staining as described for infectivity titration. All dilutions were done in triplicates and normalized to a 6 replicate virus only control. Data from neutralization experiments was presented as dose-response curves with variable slope to best fit the data and to allow for a detailed comparison between neutralization profiles across the serum dilution series. 
       Example 1 
       [0337]    Deletion of HVR1 from genotype 2a virus J6/JFH does not result in significantly reduced viral infectivity and does not incur the need for adaptive mutations. 
         [0338]    The 81 N-terminal nucleotides of the HCV envelope E2 gene, coding for the 27 N-terminal amino acids of the E2 protein, were deleted from pJ6/JFH yielding the plasmid pJ6/JFH ΔHVR1  (SEQ ID NO 2 and 8). After transfections of Huh7.5 cells with RNA transcripts of pJ6/JFH and pJ6/JFH ΔHVR1 , the percentage of infected cells was estimated by immunostaining and FFU infectivity titers were measured in cell culture supernatants derived on days 3, 6 and 8 post transfection. Both viruses spread immediately upon transfection and had very similar infectivity titers as shown in  FIGS. 1 , A &amp; B. J6/JFH ΔHVR1  supernatant from day 6 of the transfection was serially passaged to naïve Huh7.5 cells, by transfer of cell culture supernatant, derived at a time point at which virus had spread to at least 80% of cells. Direct sequence analysis of viral genomes contained in supernatant derived from first and second passage of J6/JFH ΔHVR1  at the peak of infection showed no mutations. Thus, J6/JFH ΔHVR1  was not dependent on adaptive mutations. To further investigate whether infectivity of J6/JFH was affected by deletion of HVR1, a kinetic infection experiment was set up with three different MOIs (Multiplicity of Infection, TCID 50 /number of Huh7.5 cells): 0.001, 0.005 and 0.01. The spread of both viruses correlated well with the rises in infectivity and HCV RNA titers and the two viruses behaved quite similarly at all three MOIs ( FIGS. 2 , A, B &amp; C). Thus, HVR1 deletion does not measurably inhibit infectivity of J6/JFH, even though peak virus infectivity titers of cell culture supernatant might be slightly delayed. 
       Example 2 
       [0339]    Determination of the functional borders of HVR1 by deletion of additional amino acids downstream of HVR1. 
         [0340]    pJ6/JFH ΔHVR1  with an additional deletion of 1 to 4 aa immediately downstream of HVR1 were generated and tested in cell culture. Supernatant from day 6 post transfection was titrated twice for infectivity (TCID 50 ) to ascertain viability of the generated constructs. This showed that J6/JFH ΔHVR1  tolerates the removal of 1 aa downstream of HVR1, is attenuated by the removal of 2 aa and is rendered non-infectious by deletions of 3 and 4 additional aa ( FIGS. 3  A &amp; B). This new data lends credence to the original classification of HVR1, which was based on sequence variability, by linking HVR1 truncation extension downstream in J6/JFH ΔHVR1  to reduced virus viability. 
       Example 3 
       [0341]    Deletion of HVR1 across all 6 major genotypes. 
         [0342]    H77/JFH1 T2700C,A4080T  (1a/2a) 
         [0343]    The HVR1 region corresponding to the 27 N-terminal aa of E2 was deleted in pH77/JFH1 T2700C,A4080T , and yielding the plasmid pH77/JFH1 T2700C,A4080T,ΔHVR1  (SEQ ID NO 1 and 7). A transfection of H77/JFH1 T2700c,A4080T,ΔHVR1  was set up in triplicates. H77/JFH1 T2700C,A4080T,ΔHVR1  was highly attenuated in all three transfections with no immediate increase in the percentage of infected cells ( FIG. 4 ), although very low infectivity was evident in TCID 50  titration of cell culture supernatant from day 3 (data not shown). However, infected cells persisted and on day 56, in two out of three transfection experiments, viral spread that eventually lead to infection of almost the entire cell culture was observed. At the peak of infection, viral genomes were extracted and sequenced as described. Interestingly, both viruses had a combination of two mutations in the envelope genes and in each set of mutations there was a mutation either in HVR2 or HVR3 (Table 1). In reverse genetic studies, H77/JFH1 T2700c,A4080T,ΔHVR1  were tested with the identified four envelope mutations singly or in the two observed combinations. The resulting 6 virus constructs were set up in a transfection alongside the original pH77/JFH1 T2700c,A4080T,ΔHVR1 . The transfection data is shown in  FIGS. 5 , A &amp; B and clearly shows that the HVR1 deleted constructs with either of the two envelope mutation combinations (H77/JFH1 (A1122G,A1671G),T2700C,A4080T,ΔHVR1 : SEQ ID NO 13 and 16, H77/JFH1 (A1766G,T2538C),T2700C,A4080T,ΔHVR1 : SEQ ID NO 14 and 17) spreads as quickly as the parental virus. In contrast, the single mutation constructs did not. However, from the supernatant infectivity titration it is evident, that these two viruses are still attenuated, reaching infectivity titers of 10 2,7  and 10 3,0  FFU/ml respectively on day 8 as compared to 10 3,8  FFU/ml for H77/JFH1 T2700C,A4080T , on day 8 while viruses with single mutations had infectivity titers below 10 2,0  FFU/ml on all days. 
         [0344]    J4/JFH1 T1389C,A1590G,  (1b/2a) 
         [0345]    The HVR1 motif was deleted in pJ4/JFH1 T2996c,A4827T , corresponding to the 27 N-terminal aa of E2, and yielding the plasmid pJ4/JFH1 T2996C,A4827T,ΔHVR1  (SEQ ID 19 and 22). A transfection was set up with pJ4/JFH1 T2996C,A4827T,ΔHVR1 . The virus spread immediately, but only to about 60-70% of the cells and had very slow spread in viral passaging of supernatant. The virus was sequenced after spread. Transfection data is summarized in  FIGS. 6 , A &amp; B and shows that the HVR1 deleted virus is about 20-fold less infectious than the parental J4/JFH1 T2996C,A4827T . Viruses identified in 1 st  and 2 nd  passage of J4/JFH1 T2996C,A4827T,ΔHVR1  are shown in Table 2. 
         [0346]    J8/JFH1 (2b/2a) 
         [0347]    The HVR1 motif was deleted in pJ8/JFH1, corresponding to the 27 N-terminal aa of E2, and yielding the plasmid pJ8/JFH1 ΔHVR1  (SEQ ID 20 and 23). A transfection was set up with pJ8/JFH1 ΔHVR1 . The virus did not spread immediately. 1 st  passage viral supernatants were sequenced once they spread. The mutation T1574A was seen in two separate 1 st  viral passages and was introduced into J8/JFH1 ΔHVR1  for reverse genetic studies. This was set up in a transfection alongside J8/JFH1 and J8/JFH1 ΔHVR1  Transfection data is summarized in  FIGS. 7  A and B and shows that T1574A is clearly adapting the HVR1 deleted virus, although J8/JFH1 (T1574A),ΔHVR1  is still about 10-fold less infectious than the parental J8/JFH1 (J8/JFH1 (T1574A),ΔHVR1  SEQ ID NO: 21 &amp; 24). Viruses identified in 1 st  passages of J8/JFH1 ΔHVR1  are shown in Table 3. 
         [0348]    S52/JFH1 T2718G,T7160C , (3a/2a) 
         [0349]    The HVR1 motif was deleted in pS52/JFH1 T2718G,T7160C , corresponding to the 27 N-terminal aa of E2, and yielding the plasmid pS52/JFH1 T2718G,T7160C,ΔHVR1  (SEQ ID NO 3 and 9). In a transfection experiment, S52/JFH1 T2718G,T7160C,ΔHVR1  spread immediately, however, delayed viral spread in a first passage as well as TCID 50  infectivity assays of both transfection and 1 st  passage (data not shown) indicated that the virus was attenuated. Growth kinetic improved upon serial passages (data not shown) and the HCV ORFs were sequenced in passages 2 and 4 once virus had spread to at least 80% infected cells. In both sequences a mutation in the transmembrane domain of E1 was identified corresponding to plasmid nucleotide change C1446T (Table 4). This mutation was introduced into both pS52/JFH 1 T2718G,T7160C  and pS52/JFH 1 T2718G,T7160C,ΔHVR1  (PS52/JFH1 (C1446T),T2718G,T7160C,ΔHVR1 : SEQ ID NO 15 and 18). A transfection was set up including S52/JFH1 (C1446T),T2718G,T7160C,ΔHVR1 , S52/JFH1 T2718G,T7160C,ΔHVR1  and S52/JFH1 (C1446T),T2718G,T7160C  alongside S52/JFH1 T2718G,T7160C . Of these only pS52/JFH1 T2718G,T7160C,ΔHVR1  did not spread immediately and the suggested lower infectivity was confirmed by infectivity titration of days 3 and 6 ( FIGS. 8 , A &amp; B). This data clearly shows that the E1 mutation C1446T adapts the virus quite effectively to the HVR1 deletion, but does not boost infectivity of the parental S52/JFH1 T2718G,T7160C  virus. 
         [0350]    ED43/JFH1 A2819G,A3269T  (4a/2a) 
         [0351]    The HVR1 motif was deleted in pED43/JFH1 A2819G,A3269T , corresponding to the 27 N-terminal aa of E2, and yielding the plasmid pED43/JFH1 A2819G,A3269T,ΔHVR1  (SEQ ID NO 4 and 10). A transfection was set up in triplicates. The transfection data in  FIG. 9  shows that ED43/JFH1 A2819G,A3269T,ΔHVR1  did not spread and no infectivity was detected in culture supernatants (data not shown). Transfections were followed until no infected cells could be detected in HCV specific immunostainings. 
         [0352]    SA13/JFH1 C3405G,A3696G , (5a/2a) 
         [0353]    The HVR1 motif was deleted in pSA13/JFH1 C3405G,A3696G , corresponding to the 27 N-terminal aa of E2, and yielding the plasmid pSA13/JFH1 C3405G,A3696G,ΔHVR1  (SEQ ID NO 5 and 11).  FIGS. 10 , A &amp; B shows the transfection data with immediate virus spread of SA13/JFH1 C3405G,A3696G,ΔHVR1  and that it was only slightly less infectious than the parental SA13/JFH1 C3405G,A3696G . 
         [0354]    HK6a/JFH1 T1389C,A1590G , (6a/2a) 
         [0355]    The HVR1 motif was deleted in pHK6a/JFH1 T1389C,A1590G , corresponding to the 26 N-terminal aa of E2, and yielding the plasmid pHK6a/JFH1 T1389C,A1590G,ΔHVR1  (SEQ ID NO 6 and 12). A transfection was set up with HK6a/JFH1 T1389C,A1590G,ΔHVR1 . The virus spread immediately and had acquired no additional mutations in sequence analysis of 2nd passage supernatant of cell culture having at least 80% infected cells. Transfection data is summarized in  FIGS. 11 , A &amp; B and shows that the HVR1 deleted virus is about ten-fold less infectious than the parental HK6a/JFH1 T1389C,A1590G . 
         [0356]    In Table 5 the viability of the HVR1 deleted viruses is summarized by listing required adaptive mutations when appropriate as well as infectivity titers determined on supernatants derived on the first days after transfection. These titers are used in the calculations of the relative infectivities compared to the respective parental viruses on the given day of transfection and the present inventors thereby show that the HVR1 deleted viruses are viable in a range of non-affected (J6) to complete disruption of infectivity (ED43). These differences are dependent on the isolate and possibly the subtype. Additionally, it is shown that H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J8/JFH1 ΔHVR1  (2b/2a) and S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a) are dependent on adaptive mutations. 
         [0357]    Accordingly, the present inventors were able to generate HVR1 motif deleted viruses of JFH1-based intra- and intergenotypic HCV recombinants H77/JFH1 T2700C,A4080T  (1a/2a), J4/JFH1 T2996C,A4827T  (1b/2a), J6/JFH (2a/2a), J8/JFH1 (2b/2a), S52/JFH1 T2718G,T7160C  (3a/2a), SA13/JFH1 C3405G,A3696G  (5a/2a) and HK6a/JFH1 T1389C,A1590G  (6a/2a). H77/JFH1 T2700C,A4080T,ΔHVR1  (1a/2a), J4/JFH1 T2996C,A4827T,ΔHVR1  (1b/2a), J8/JFH1 ΔHVR1  (2b/2a) and S52/JFH1 T2718G,T7160C,ΔHVR1  (3a/2a) required adaptive mutations in the envelope genes E1 and/or E2 to improve virus infectivity. 
       Example 4 
       [0358]    21 aa deletion N-terminally in E2 of H77/JFH1 T2700c,A4080T  (1a/2a) and ED43/JFH1 A2819G,A3269T  (4a/2a) 
         [0359]    To investigate if shorter HVR1 regions for H77/JFH1 T2700C,A4080T  and ED43/JFH1 A2819G,A3269T  were the reason why these constructs did not spread with a 27 aa HVR1 deletion the present inventors generated constructs in which 21 N-terminal amino acids of E2 were deleted. These were then set up in triplicate transfections ( FIG. 12 ). Since no improvements in viral spread were observed shorter deletions did not improve the fitness of the truncated viruses. 
       Example 5 
     Neutralization of HCV by Patient Sera 
       [0360]    Neutralization of HCV by patient sera shows distinct differences between genotypes and between identical viruses with and without HVR1. The present inventors investigated how neutralization of wt and HVR1 truncated viruses compared using the H06 serum. It is evident ( FIG. 13 , A-E) that in all direct comparisons, except for HK6a/JFH1 T1389C,A1590C  neutralization is markedly improved for the HVR1 truncated viruses. Since the amino acid sequences are identical, aside from the HVR1 truncation, the conclusion is that additional epitopes are available on the surface of the HVR1 truncated viruses, indicating that they must somehow be shielded in the wt virus particle. This is further substantiated by the much higher degree of neutralization diversity seen for the wt viruses, when compared to the complete and narrow transition from 0 to 100% neutralization at high serum dilutions for all of the HVR1 truncated viruses. The J6/JFH and S52/JFH1 T2718G,T7160C  viruses reach a plateau of neutralization suggesting at least two structurally distinct populations of viruses whereas their HVR1 truncated counterparts are both neutralized very efficiently. The H77/JFH T2700C,A4080T , SA13/JFH1 C3405G,A3696G  and HK6a/JFH1 T1389C,A1590G,ΔHVR1  all show the same pattern going toward complete neutralization stretched over a large span of the serum dilution series, indicating either that multiple populations are also present for these viruses and being neutralized at different efficiencies by the serum or that the serum targeted epitopes, though available, are not as easily accessible as for the HVR1 truncated viruses. 
         [0361]    To further substantiate these findings two wt viruses and their HVR1 truncated counterparts were selected, based on differences in the wt neutralization pattern. These viruses were subjected to neutralization with purified H06 IgG as well as two different sera; AA and SA3 ( FIG. 15  A-F). The trend of the H06 serum is seen again for the purified H06 IgG though it is not as clearly defined, showing that the neutralizing effects seen for full serum can be attributed to specific, neutralizing IgG antibodies present in the patient serum. Both the AA and the SA3 sera effectively block J6/JFH ΔHVR1 , much like what was seen for H06, but the corresponding J6/JFH is not significantly neutralized even at the lowest serum dilution of 1:50. 
         [0362]    To investigate whether HVR1 in fact contains neutralization epitopes for the wt viruses, the present inventors used the rabbit hyper-immune serum, LMF87, raised against an HVR1 peptide from H77 in a neutralizing assay against H77/JFH1 T2700C,A4080T  and H77/JFH1 (A1766G,T258C),T2700C,A4080T,ΔHVR1  ( FIG. 14 ). It clearly demonstrates a significant effect against the wt virus and no significant effect against the HVR1 truncated virus, lacking the HVR1 epitopes against which the hyper-immune serum was raised. This shows that HVR1 is, indeed, displayed on the surface of the wt virus particle, despite the probable shielding of other epitopes that are available for the HVR1 truncated viruses. The neutralizing effect against HVR1 epitopes could be a purely steric one, but it might also suggest a functional role for HVR1 in the wt virus particle. 
       Example 6 
       [0363]    Density of HCV RNA and infectious particles of virus with and without HVR1. To investigate the reason why HVR1 truncated viruses were continuously being neutralized more effectively than their non-truncated counterparts the present inventors ran density gradients of the viruses J6/JFH, S52/JFH1 T2718G,T7160C , SA13/JFH1 C3405G,A3696G  and HK6a/JFH1 T1389C,A1590G  against the respective HVR1 deleted counterparts and assessed infectivity titers in the different fractions ( FIGS. 16  A, B, C &amp; D). No difference is observed when comparing HCV RNA distributions of the density analysis. However, clear differences between HVR1 truncated and non-truncated viruses are seen for density of infectious virus. HVR1 deletion changed the density of infectious virus from between 1.0-1.1 g/ml to a single peak around 1.1 g/ml. This shift suggests that virus particles with a high degree of lipid association are not infectious in the absence of HVR1. The increased homogeneity of the infectious virus particles coupled with a low lipid association might well be what is reflected in the observed neutralization data. 
       Figure Legends 
     FIG. 1 
       [0364]    Transfection of Huh7.5 cells with J6/JFH with and without HVR1. 
         [0365]    HCV RNA was transfected into Huh7.5 cells to test the performance of J6/JFH ΔHVR1  as compared to J6/JFH. A GND motif replication deficient J6/JFH virus (GND) was used as negative control. A: Percentage of infected cells was estimated by fluorescence microscopy after immunostaining for HCV proteins Core or NS5A to quantify viral spread. B: Infectivity titers were determined as FFU/mL using three independent ten-fold dilution series of each cell culture supernatant from the indicated day of the transfection experiment (cut-off: 1.7). Means are shown and Error bars are SD. 
       FIG. 2 
       [0366]    Growth kinetics of J6/JFH with and without HVR1 after inoculation with different MOI. 
         [0367]    Huh7.5 cells were infected with three different MOIs of both J6/JFH and J6/JFH ΔHVR1 . A: Cells were immunostained for HCV proteins Core or NS5A to quantify viral spread. B: Three replicates of a ten-fold dilution series of cell culture supernatants from the indicated day of transfection was used in HCV infectivity titrations (cut-off: 2.7 logs) of J6/JFH and J6/JFH ΔHVR1  (black bars, left Y-axis). C: A single HCV RNA titration using TaqMan realtime PCR (cut-off: 2.7 logs, grey bars, right Y-axis). 
       FIG. 3 
       [0368]    Transfection of Huh7.5 cells with J6/JFH, J6/JFH ΔHVR1  (Corresponding to aa deletion of 384-410), J6/JFH Δ384-411 , J6/JFH Δ384-412 , J6/JFH Δ384-413  and J6/JFH Δ384-414 . 
         [0369]    RNA transcripts were transfected into Huh7.5 cells to test the performance of J6/JFH ΔHVR1  (Corresponding to aa deletion of 384-410), J6/JFH Δ384-411 , J6/JFH Δ384-412 , J6/JFH Δ384-413  and J6/JFH Δ384-414  as compared to J6/JFH. A GND motif replication deficient J6/JFH virus (GND) was used as negative control. A: Cells were immunostained for HCV proteins Core or NS5A to quantify viral spread. B: Ten-fold dilution series of cell culture supernatants from day 6 of transfection was used in two separate HCV infectivity titrations by TCID50. 
       FIG. 4 
       [0370]    Transfection of Huh7.5 cells with H77/JFH1 T2700C,A4080T  with and without HVR1. 
         [0371]    HCV RNA was transfected into Huh7.5 cells to test the performance of H77/JFH1 T2700C,A4080T,ΔHVR1  as compared to H77/JFH1 T2700C,A4080T  with a GND motif replication deficient J6/JFH virus (GND). H77/JFH1 T2700C,A4080T,ΔHVR1  was set up in three separate transfections; transfection 1 (upward triangles), transfection 2 (downward triangles) and transfection 3 (diamonds). Cells were immunostained for HCV proteins Core or NS5A to quantify viral spread. 
       FIG. 5 
       [0372]    Transfection of Huh7.5 cells testing efficacy of adaptive mutations identified for H77/JFH1 T2700C,A4080T,ΔHVR1 . 
         [0373]    HCV RNA was transfected into Huh7.5 cells to test the performance of the mutations A1122G, A1671G, A1766G and T2538C on viability of H77/JFH1 T2700C,A4080T,ΔHVR1  as compared to H77/JFH1 T2700C,A4080T  with a GND motif replication deficient J6/JFH virus (GND). A: Cells were immunostained for HCV proteins Core or NS5A to quantify viral spread. B: Three independent ten-fold dilution series of cell culture supernatants from the indicated day of transfection was used in HCV infectivity titrations (cut-off: 1.7 logs). Single mutation constructs showed slightly improved infectivity over H77/JFH1 T2700C,A4080T,ΔHVR1  (trend below assay cut-off and therefore not shown by barplot). Means are shown and Error bars are SD. 
       FIG. 6 
       [0374]    Transfection of Huh7.5 cells with J4/JFH1 T2996C,A4827T  with and without HVR1. 
         [0375]    HCV RNA was transfected into Huh7.5 cells to test the performance of J4/JFH1 T2996C,A4827T,ΔHVR1  as compared to J4/JFH1 T2996C,A4827T . A GND motif replication deficient J6/JFH virus (GND) was used as negative control. A: Percentage of infected cells was estimated by fluorescence microscopy after immunostaining for HCV proteins Core or NS5A to quantify viral spread. B: Infectivity titers were determined as FFU/mL using three independent ten-fold dilution series of each cell culture supernatant from the indicated day of the transfection experiment (cut-off: 1.7). Means are shown and Error bars are SD. 
         [0376]    
       FIG. 7 
     
         [0377]    Transfection of Huh7.5 cells with J8/JFH1, J8/JFH1 ΔHVR1  and J8/JFH1 (T1574A),ΔHVR1 . 
         [0378]    HCV RNA was transfected into Huh7.5 cells to test the performance of the putative adaptive mutation T1574A on J8/JFH ΔHVR1  viability as compared to J8/JFH1 and J8/JFH1 ΔHVR1 . A GND motif replication deficient J6/JFH virus (GND) was used as negative control. A: Percentage of infected cells was estimated by fluorescence microscopy after immunostaining for HCV proteins Core or NS5A to quantify viral spread. B: Infectivity titers were determined as FFU/mL using three independent ten-fold dilution series of each cell culture supernatant from the indicated day of the transfection experiment (cut-off: 1.7). Means are shown and Error bars are SD. 
       FIG. 8 
       [0379]    Transfection of Huh7.5 cells to test efficacy adaptive mutation C1446T on S52/JFH1 T2718G,T7160C  and S52/JFH1 T2718G,T7160C,ΔHVR1 . 
         [0380]    HCV RNA was transfected into Huh7.5 cells to test the performance of the effect of C1446T on S52/JFH1 T2718G,T7160C  and S52/JFH1 T2718G,T7160C,ΔHVR1  as compared to S52/JFH1 T2718G,T7160C  with a GND motif replication deficient J6/JFH virus (GND) as negative control. A: Cells were immunostained for HCV proteins Core or NS5A to quantify viral spread. B: Three independent ten-fold dilution series of cell culture supernatants from the indicated day of transfection was used in HCV infectivity titrations (cut-off: 1.7 logs). 
         [0381]    
       FIG. 9 
     
         [0382]    Transfection of Huh7.5 cells with ED43/JFH1 A2819G,A3269T  with and without HVR1 
         [0383]    HCV RNA was transfected into Huh7.5 cells to test the performance of ED43/JFH1 A2819G,A3269T,ΔHVR1  as compared to ED43/JFH1 A2819G,A3269T  with a GND motif replication deficient J6/JFH virus (GND). ED43/JFH1 A2819G,A3269T,ΔHVR1  was set up in three separate transfections; transfection 1 (upward triangles), transfection 2 (downward triangles) and transfection 3 (diamonds). Cells were immunostained for HCV proteins Core or NS5A to quantify viral spread. 
       FIG. 10 
       [0384]    Transfection of Huh7.5 cells with SA13/JFH1 C3405G,A3696G  with and without HVR1. 
         [0385]    HCV RNA was transfected into Huh7.5 cells to test the performance of SA13/JFH1 C3405G,A3696G,ΔHVR1  as compared to SA13/JFH1 C3405G,A3696G . A GND motif replication deficient J6/JFH virus (GND) was used as negative control. A: Percentage of infected cells was estimated by fluorescence microscopy after immunostaining for HCV proteins Core or NS5A to quantify viral spread. B: Infectivity titers were determined as FFU/mL using three independent ten-fold dilution series of each cell culture supernatant from the indicated day of the transfection experiment (cut-off: 1.7). Means are shown and Error bars are SD. 
       FIG. 11 
       [0386]    Transfection of Huh7.5 cells with HK6a/JFH1 T1389C,A1590G  with and without HVR1. 
         [0387]    HCV RNA was transfected into Huh7.5 cells to test the performance of HK6a/JFH1 T1389C,A1590G,ΔHVR1  as compared to HK6a/JFH1 T1389C,A1590G  with a GND motif replication deficient J6/JFH virus (GND). A: Cells were immunostained for HCV proteins Core or NS5A to quantify viral spread. B: Three independent ten-fold dilution series of cell culture supernatants from the indicated day of transfection was used in HCV infectivity titrations (cut-off: 1.7). 
         [0388]    
       FIG. 12 
     
         [0389]    Transfection of Huh7.5 cells with 21 aa N-terminal deletion of E2 for H77/JFH1 T2700C,A4080T  and ED43/JFH1 A2819G,A3269T . 
         [0390]    HCV RNA was transfected into Huh7.5 cells to test the performance of the 21 aa N-terminal deletions of E2 for H77/JFH1 T2700C,A4080T  and ED43/JFH1 A2819G,A3269T  as compared to their respective parental viruses (both 21 aa constructs set up in triplicates). A GND motif replication deficient J6/JFH virus (GND) was used as negative control. Percentage of infected cells was estimated by fluorescence microscopy after immunostaining for HCV proteins Core or NS5A to quantify viral spread. 
         [0391]    
       FIG. 13 
     
         [0392]    Neutralization with HCV patient serum H06 of HVR1 truncated viruses is significantly more effective than that of their wt counterparts. 
         [0393]    Huh7.5 cells were plated at 6000/well in 96 well plates and incubated ON at 37° C. The next day the indicated viruses were incubated with the patient serum for 1 h at 37° C. prior to adding the virus/serum mix to the cells in 100 μl/well in triplicates. The virus was allowed to enter the cells for 3 h prior to washing and addition of 200 μl of fresh medium. After 48 h incubation and immunostaining for HCV NS5A antigen, FFU/well was counted; % inhibition of entry was calculated by normalization to the wells with virus only. 
       FIG. 14 
       [0394]    Neutralization of H77/JFH1 T2700C,A4080T  with and without HVR1 with H77 HVR1 specific rabbit hyper-immune serum, LMF87. 
         [0395]    Huh7.5 cells were plated at 6000/well in 96 well plates and incubated ON at 37° C. The next day viruses H77/JFH1 T2700C,A4080T  and H77/JFH1 (A1766G,T2538C),T2700C,A4080T,ΔHVR1  were incubated with the patient serum for 1 h at 37° C. prior to adding the virus/serum mix to the cells in 100 μl/well in triplicates. The virus was allowed to enter the cells for 3 h prior to washing and addition of 200 μl of fresh medium. After 48 h incubation and immunostaining for HCV NS5A antigen, FFU/well was counted; % inhibition of entry was calculated by normalization to the wells with virus only. 
       FIG. 15 
       [0396]    The improved neutralization of HVR1 truncated viruses is seen for both purified IgG from H06 and two other patient sera: AA and SA3. 
         [0397]    Huh7.5 cells were plated at 6000/well in 96 well plates and incubated ON at 37° C. The next day the indicated viruses were incubated with the purified IgG or patient serum for 1 h at 37° C. prior to addition of the virus/serum (or IgG) mix to the cells at 100 μl/well in triplicates. The virus was allowed to enter the cells for 3 h prior to washing and addition of 200 μl of fresh medium. After 48 h incubation and immunostaining for HCV NS5A antigen, FFU/well were counted; % inhibition of entry was calculated by normalization to the wells with only virus 
       FIG. 16 
       [0398]    Density centrifugation of J6/JFH, S52/JFH1 T2718G,T7160C , SA13/JFH1 C3405G,A3696G  and HK6a/JFH1 T1389C,A1590G  with and without HVR1. 
         [0399]    Four steps of iodixanol/PBS mixtures were prepared at 10, 20, 30 and 40% iodixanol. 2.5 ml of these were then layered on top of each other and left upright for 24 h at 4° C. Virus was concentrated to a volume of ˜200 μl in Amicon centrifugation columns and then added to the top of the iodixanol gradient. Next the gradients were centrifuged at 150000×RCF for 18 h at 4° C. Afterwards the tube was punctured at the bottom and 18 550 μl fractions were collected. Density of each fraction was determined by weighing 400 μl from each fraction. Fractions were HCV infectivity titrated (A &amp; B) and HCV RNA titrated (C &amp; D). 
       Tables 
       [0400]      
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Putative adaptive mutations in the envelope genes for H77/JFH1 T2700C,A4080T,ΔHVR1 . 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 HCV gene 
                   
                 E1 
                 E1 
                 E1 
                 E2 
                 E2 
                 E2 
                 E2 
                 E2 
               
               
                 Nucleotide number 
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 pH77/JFH1 T2700C,A4080T  position 
                   
                 1122 
                 1383 
                 1421 
                 1628 
                 1671 
                 1766 
                 2385 
                 2538 
               
               
                 H77 abs. ref. (AF009606) 
                   
                 1123 
                 1384 
                 1422 
                 1629 
                 1672 
                 1767 
                 2386 
                 2539 
               
               
                 plasmid nucleotide 
                   
                 A 
                 T 
                 T 
                 A 
                 A 
                 A 
                 T 
                 C 
               
               
                 H77/JFH1 T2700C,A4080T,ΔHVR1  transfections 
                 Titer I  (day) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 H77/JFH1 T2700C,A4080T,ΔHVR1 , Transfection 1 
                 2.9 (56) 
                 G/a 
                 — 
                 — 
                 — 
                 G/a 
                 — 
                 — 
                 — 
               
               
                 H77/JFH1 T2700C,A4080T,ΔHVR1 , Transfection 3 
                 2.9 (56) 
                 — 
                 — 
                 — 
                 — 
                 — 
                 G/a 
                 — 
                 T 
               
               
                 Mutated H77/JFH1 T2700C,A4080T,ΔHVR1  transfections 
                 Titer I  (day) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 H77/JFH1 T2700C,A4080T,ΔHVR1   
                 2.7 (55) 
                 — 
                 — 
                 C 
                 — 
                 G/a 
                 — 
                 — 
                 — 
               
               
                   
               
               
                 H77/JFH1 (A1122G),T2700C,A4080T,ΔHVR1   
                 3.2 (50) 
                 
                   
                             
                     
                         
                         
                     
                   
                 
                 — 
                 — 
                 G/a 
                 G 
                 — 
                 A/t 
                 — 
               
               
                   
               
               
                 H77/JFH1 (A1671G),T2700C,A4080T,ΔHVR1   
                 2.6 (31) 
                 — 
                 T/g 
                 — 
                 — 
                 
                   
                             
                     
                         
                         
                     
                   
                 
                 — 
                 — 
                 C/t 
               
               
                   
               
               
                 H77/JFH1 (A1766G),T2700C,A4080T,ΔHVR1   
                 3.1 (50) 
                 — 
                 — 
                 — 
                 — 
                 G/a 
                 
                   
                             
                     
                         
                         
                     
                   
                 
                 — 
                 C/t 
               
               
                   
               
               
                 H77/JFH1 (C2538T),T2700C,A4080T,ΔHVR1   
                 2.1 (24) 
                 — 
                 — 
                 — 
                 — 
                 — 
                 — 
                 — 
                 
                   
                             
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 H77/JFH1 (A1122G,A1671G),T2700C,A4080T,ΔHVR1   
                 3.0 (15 II ) 
                 
                   
                             
                     
                         
                         
                     
                   
                 
                 — 
                 — 
                 — 
                 
                   
                             
                     
                         
                         
                     
                   
                 
                 — 
                 T/a 
                 — 
               
               
                   
               
               
                 H77/JFH1 (A1766G,C2538T),T2700C,A4080T,ΔHVR1   
                 3.2 (15 II ) 
                 — 
                 — 
                 — 
                 — 
                 — 
                 
                   
                             
                     
                         
                         
                     
                   
                 
                 — 
                 
                   
                             
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 Amino Acid number 
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 pH77/JFH1 T2700C,A4080T  position 
                   
                  261 
                  348 
                  361 
                  430 
                  444 
                  476 
                  682 
                  733 
               
               
                 H77 abs. ref. (AF009606) 
                   
                  261 
                  348 
                  361 
                  430 
                  444 
                  476 
                  682 
                  733 
               
               
                 Change 
                   
                 H→R 
                 I→S 
                 Y→H 
                 N→D 
                 Q→R 
                 N→D 
                 L→Q 
                 S→F 
               
               
                   
               
               
                   I Titer is the mean log10 of three independent FFU infectivity titrations. 
               
               
                   II Virus transfection was passaged on day 10 and FFU titration was carried out on 1st passage virus on day 15. 
               
               
                 Shaded cells are mutations that were present in the construct upon transfection. 
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Putative adaptive mutations in the envelope genes for J4/JFH1 T2996C, A4827T, ΔHVR1 . 
               
             
          
           
               
                 HCV gene 
                   
                 E1 
                 E1 
                 E2 
                 E2 
                 E2 
                 E2 
               
               
                   
               
               
                 Nucleotide number 
                   
                   
                   
                   
                   
                   
                   
               
               
                 pJ4/JFH1 T2996C, A4827T  position 
                   
                 1236 
                 1428 
                 1643 
                 2066 
                 2225 
                 2468 
               
               
                 H77 abs. ref. (AF009606)  
                   
                 1237 
                 1429 
                 1644 
                 2067 
                 2226 
                 2469 
               
               
                 plasmid nucleotide 
                   
                 A 
                 C 
                 A 
                 A 
                 G 
                 G 
               
               
                   
               
               
                 J4/JFH1 T2996C, A4827T, ΔHVR1 , 1st transfection 
                 Titer I  (day) 
               
               
                   
               
               
                 1st passage 
                 below detection II  (84) 
                 — 
                 T 
                 C 
                 — 
                 — 
                 C 
               
               
                 2nd passage 
                 4.1 (22) 
                 G/a 
                 T 
                 C 
                 G/a 
                 A/g 
                 C 
               
               
                   
               
               
                 Amino Acid number 
                   
                   
                   
                   
                   
                   
                   
               
               
                 pJ4/JFH1 T2996C, A4827T  position 
                   
                 299 
                 363 
                 435 
                 576 
                 629 
                 710 
               
               
                 H77 abs. ref. (AF009606) 
                   
                 299 
                 363 
                 435 
                 576 
                 629 
                 710 
               
               
                 Change 
                   
                 E-G 
                 S-F 
                 T-P 
                 N-D 
                 V-I 
                 V-L 
               
               
                   
               
               
                   I Titer is expressed as the mean log10 of three independent FFU infectivity titrations. 
               
               
                   II The low titer at this timepoint is likely caused by a prolonged infection of the cells of about 10-20% 
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                 Putative adaptive mutations in the envelope genes for J8/JFH1 ΔHVR1 . 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 HCV gene 
                   
                 E2 
                 E2 
                 E2 
                 E2 
                 E2 
                 E2 
               
               
                 Nucleotide  
                   
                   
                   
                   
                   
                   
                   
               
               
                 number 
                   
                   
                   
                   
                   
                   
                   
               
               
                 pJ8/JFH1  
                   
                 1571 
                 1572 
                 1574 
                 1580 
                 1652 
                 1941 
               
               
                 position 
                   
                   
                   
                   
                   
                   
                   
               
               
                 H77 abs. ref.  
                   
                 1572 
                 1573 
                 1575 
                 1581 
                 1653 
                 1936 
               
               
                 (AF009606) 
                   
                   
                   
                   
                   
                   
                   
               
               
                 plasmid  
                   
                 C 
                 T 
                 T 
                 A 
                 A 
                 A 
               
               
                 nucleotide 
                   
                   
                   
                   
                   
                   
                   
               
               
                 J8/JFH1 ΔHVR1 ,  
                 Titer I    
                   
                   
                   
                   
                   
                   
               
               
                 1st transfection 
                 (day) 
                   
                   
                   
                   
                   
                   
               
               
                 J8/JFH1 ΔHVR1 ,  
                 3.5 (24 II ) 
                 — 
                 — 
                 A 
                 — 
                 — 
                 A/c 
               
               
                 Transfection 1 
                   
                   
                   
                   
                   
                   
                   
               
               
                 J8/JFH1 ΔHVR1 ,  
                 4.4 (15 II ) 
                 G/C 
                 G/T 
                 — 
                 A/g 
                 T/A 
                 — 
               
               
                 Transfection 2 
                   
                   
                   
                   
                   
                   
                   
               
               
                 J8/JFH1 ΔHVR1 ,  
                 3.3 (15 II ) 
                 — 
                 — 
                 A 
                 — 
                 — 
                 — 
               
               
                 Transfection 3 
                   
                   
                   
                   
                   
                   
                   
               
               
                 J8/JFH1 ΔHVR1 ,  
                 Titer I    
                   
                   
                   
                   
                   
                   
               
               
                 1st transfection 
                 (day) 
                   
                   
                   
                   
                   
                   
               
               
                   
               
               
                 J8/ JFH1 ΔHVR1,   T1574A   
                 1.8 (16) 
                 — 
                 — 
                 
                   
                             
                     
                         
                         
                     
                   
                 
                 — 
                 — 
                 — 
               
               
                   
               
               
                 Amino Acid  
                   
                   
                   
                   
                   
                   
                   
               
               
                 number 
                   
                   
                   
                   
                   
                   
                   
               
               
                 pJ8/JFH1  
                   
                  411 
                  411 
                  412 
                  414 
                  438 
                  534 
               
               
                 position 
                   
                   
                   
                   
                   
                   
                   
               
               
                 H77 abs. ref.  
                   
                  411 
                  411 
                  412 
                  414 
                  438 
                  532 
               
               
                 (AF009606) 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Change 
                   
                 L-V 
                 L-R 
                 Y-N 
                 I-V 
                 M-L 
                 N-T 
               
               
                   
               
               
                   I Titer is expressed as the mean log10 of three independent FFU infectivity titrations. 
               
               
                   II All viruses were sequenced in a first passage of the transfection at the indicated day. 
               
               
                   III Gray cells signify that the mutation was present in the construct upon transfection. 
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                 Putative adaptive mutations in the envelope 
               
               
                 genes for S52/JFH1 T2718G,T7160C,ΔHVR1 . 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Gene region 
                   
                 TM 
               
               
                   
                 Nucleotide number 
                   
                   
               
               
                   
                 pS52/JFH1 T2718G,T7160C  position 
                   
                 1446 
               
               
                   
                 H77 abs. ref. (AF009606) 
                   
                 1447 
               
               
                   
                 plasmid nucleotide 
                   
                 C 
               
               
                   
                 S52/JFH1 T2718G,T7160C,ΔHVR1 , 1st 
                 day 
                   
               
               
                   
                 transfection 
                   
                   
               
               
                   
                 1st passage 
                 2.6 (6)  
                 — 
               
               
                   
                 2nd passage 
                 2.7 (13) 
                 T/c 
               
               
                   
                 4th passage 
                 3.9 (6)  
                 T 
               
               
                   
                 S52/JFH1 T2718G,T7160C,ΔHVR1 , 2nd 
                 day 
                   
               
               
                   
                 transfection 
                   
                   
               
               
                   
               
               
                   
                 3rd passage 
                 3.8 (10) 
                 
                   
                             
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                   
                 Amino Acid number 
                   
                   
               
               
                   
                 pS52/JFH1 T2718G,T7160C  position 
                   
                  369 
               
               
                   
                 H77 abs. ref. (AF009606) 
                   
                  369 
               
               
                   
                 Change 
                   
                 A-V 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 HVR1 deleted HCV recombinants and viral kinetics in transfection as compared to respective parental virus. 
               
             
          
           
               
                   
                   
                 HVR1 adaptive mutations 
                 Infectivity 
                 Infectivity relative  
               
               
                   
                 Viable*  
                 (HCV gene affected) 
                 (FFU/ml)log10 
                 to parental virus            
               
               
                   
               
               
                   
                   
                   
                 Day of transfection 
                 Day of transfection 
               
             
          
           
               
                   
                   
                   
                 3 
                 6 
                 8 
                 3 
                 6 
                 8 
               
               
                 H77/JFH1 T2700C, A4080T, ΔHVR1   
                 (Y) 
                 A1122G (E1), A1671G (E2) 
                   
                   
                   
                   
                   
                   
               
               
                 
                           
                 
                   
                   
                 2.3 
                 2.4 
                 2.7 
                    10% 
                    13% 
                    10% 
               
               
                 H77/JFH1 T2700C, A4080T, ΔHVR1   
                 (Y) 
                 A1766G (E2), C2538T (E2) 
                   
                   
                   
                   
                   
                   
               
               
                 
                           
                 
                   
                   
                 2.3 
                 2.6 
                 3.0 
                    10% 
                    20% 
                    20% 
               
               
                 J4/JFH1 T2996C, A4827T, ΔHVR1   
                 (Y) 
                 — 
                 2.1 
                 1.9 
                 2.3 
                    5% 
                    2% 
                    4% 
               
               
                 J6/JFH ΔHVR1   
                 Y 
                 — 
                 4.8 
                 5.1 
                 4.0 
                    50% 
                    79% 
                    25% 
               
               
                 J8/JFH1 ΔHVR1   
                 (Y) 
                 T1574A (E2) 
                 3.1 
                 3.3 
                 3.4 
                    24% 
                    30% 
                    7% 
               
               
                 S52/JFH1 T2718G, T7160C, ΔHVR1   
                 (Y) 
                 C1446T (E1) 
                 3.9 
                 3.8 
                 — 
                   100% 
                    63% 
                 — 
               
               
                 ED43/JFH1 A2819G, A3269T   
                 N 
                 — 
                 — 
                 — 
                 — 
                  ~0% 
                  ~0% 
                  ~0% 
               
               
                 SA13/JFH1 C3405G, A3696G, ΔHVR1   
                 Y 
                 — 
                 4.5 
                 4.1 
                 4.3 
                    13% 
                    16% 
                    25% 
               
               
                 HK6a/JFH1 T1389C, A1590G, ΔHVR1   
                 Y 
                 — 
                 2.7 
                 2.8 
                 3.0 
                    10% 
                    13% 
                    13% 
               
               
                   
               
               
                 *Viability of HVR1 deleted construct without any adaptive mutations. Y: Spreads immediately and does not acquire adaptive mutations in 1st passage. (Y): Virus is infectious, but acquires adaptive mutations. N: Virus is non-infectious. 
               
               
                             Transfection 1 of H77/JFH1 T2700C, A4080T, ΔHVR1  construct. 
               
               
                             Transfection 3 of H77/JFH1 T2700C, A4080T, ΔHVR1  construct. 
               
               
                            calculated as infectivity of HVR1 deleted virus on given day of transfection divided by infectivity of parental virus on given day of transfection. 
               
             
          
         
       
     
       REFERENCES 
       [0000]    
       
         Altschul S F, Lipman D J. Protein database searches for multiple alignments. Proc Natl Acad Sci USA 1990 July; 87(14):5509-5513. 
         Cerino, A., Bissolati, M., Cividini, A., Nicosia, A., Esumi, M., Hayashi, N., Mizuno, K., Slobbe, R., Oudshoorn, P., Silini, E. et al. (1997) J. Med. Virol. 51, 1-5. 
         Forms, X., Thimme, R., Govindarajan, S., Emerson, S. U., Purcell, R. H., Chisari, F. V., &amp; Bukh, J. (2000) Proc. Natl. Acad. Sci. U.S. A 97, 13318-13323. 
         Gottwein, J. M., Scheel, T. K., Hoegh, A. M., Lademann, J. B., Eugen-Olsen, J., Lisby, G., &amp; Bukh, J. (2007) Gastroenterology 133, 1614-1626. 
         Kato, T., T. Date, M. Miyamoto, A. Furusaka, K. Tokushige, M. Mizokami, and T. Wakita. 2003. Efficient replication of the genotype 2a hepatitis C virus subgenomic replicon. Gastroenterology 125:1808-1817. 
         Kato, T., A. Furusaka, M. Miyamoto, T. Date, K. Yasui, J. Hiramoto, K. Nagayama, T. Tanaka, and T. Wakita. 2001. Sequence analysis of hepatitis C virus isolated from a fulminant hepatitis patient. J Med Virol 64:334-339. 
         Lindenbach, B. D., M. J. Evans, A. J. Syder, B. Wolk, T. L. Tellinghuisen, C. C. Liu, T. Maruyama, R. O. Hynes, D. R. Burton, J. A. McKeating, and C. M. Rice. 2005. Complete replication of hepatitis C virus in cell culture. Science 309:623-626. 
         Lindenbach B D, Meuleman P, Ploss A, Vanwolleghem T, Syder A l, McKeating J A, Lanford R E, Feinstone S M, Major M E, Leroux-Roels G, Rice CM. Cell culture-grown hepatitis C virus is infectious in vivo and can be recultured in vitro. Proc Natl Acad Sci USA. 2006 Mar. 7; 103(10):3805-9. Epub 2006 Feb. 16. 
         Manzin, A., Solforosi, L., Debiaggi, M., Zara, F., Tanzi, E., Romano, L., Zanetti, A. R., &amp; Clementi, M. (2000) J. Virol. 74, 4327-4334. 
         Mondelli, M. U., Cerino, A., Segagni, L., Meola, A., Cividini, A., Silini, E., &amp; Nicosia, A. (2001) Antiviral Res. 52, 153-159. 
         Ray, S. C., Wang, Y. M., Laeyendecker, O., Ticehurst, J. R., Villano, S. A., &amp; Thomas, D. L. (1999) J. Virol. 73, 2938-2946. 
         Scarselli, E., Ansuini, H., Cerino, R., Roccasecca, R. M., Acali, S., Filocamo, G., Traboni, C., Nicosia, A., Cortese, R., &amp; Vitelli, A. (2002) EMBO J. 21, 5017-5025. 
         Steinmann, E., Penin, F., Kallis, S., Patel, A. H., Bartenschlager, R., &amp; Pietschmann, T. (2007) PLoS. Pathog. 3, e103. 
         Scheel, T. K., Gottwein, J. M., Jensen, T. B., Prentoe, J. C., Hoegh, A. M., Alter, H. J., Eugen-Olsen, J., &amp; Bukh, J. (2008) Proc. Natl. Acad. Sci. U.S. A 105, 997-1002. 
         Wakita, T., T. Pietschmann, T. Kato, T. Date, M. Miyamoto, Z. Zhao, K. Murthy, A. Habermann, H. G. Krausslich, M. Mizokami, R. Bartenschlager, and T. J. Liang. 2005. Production of infectious hepatitis C virus in tissue culture from a cloned viral genome. Nat Med 11:791-796. 
         Zhong, J., P. Gastaminza, G. Cheng, S. Kapadia, T. Kato, D. R. Burton, S. F. Wieland, S. L. Uprichard, T. Wakita, and F. V. Chisari. 2005. Robust hepatitis C virus infection in vitro. Proc Natl Acad Sci USA 102:9294-9299.