bluuebunny/crossref_metadata_2025_split huggingface dataset:
Codon Substitution Mutations at Two Positions in the L Polymerase Protein of Human Parainfluenza Virus Type 1 Yield Viruses with a Spectrum of Attenuation In Vivo and Increased Phenotypic Stability In Vitro
Authors: McAuliffe Josephine M. , Surman Sonja R. , Newman Jason T. , Riggs Jeffrey M. , Collins Peter L. , Murphy Brian R. , Skiadopoulos Mario H. 
Published: January 2004

ABSTRACT

The Y942H and L992F temperature-sensitive (
ts
) and attenuating amino acid substitution mutations, previously identified in the L polymerase of the HPIV3
cp
45 vaccine candidate, were introduced into homologous positions of the L polymerase of recombinant human parainfluenza virus type 1 (rHPIV1). In rHPIV1, the Y942H mutation specified the
ts
phenotype in vitro and the attenuation (
att
) phenotype in hamsters, whereas the L992F mutation specified neither phenotype. Each of these codon mutations was generated by a single nucleotide substitution and therefore had the potential to readily revert to a codon specifying the wild-type amino acid residue. We introduced alternative amino acid assignments at codon 942 or 992 as a strategy to increase genetic stability and to generate mutants that exhibit a range of attenuation. Twenty-three recombinants with codon substitutions at position 942 or 992 of the L protein were viable. One highly
ts
and
att
mutant, the Y942A virus, which had a difference of three nucleotides from the codon encoding a wild-type tyrosine, also possessed a high level of genetic and phenotypic stability upon serial passage in vitro at restrictive temperatures compared to that of the parent Y942H virus, which possessed a single nucleotide substitution. We obtained mutants with substitutions at position 992 that, in contrast to the L992F virus, possessed the
ts
and
att
phenotypes. These findings identify the use of alternative codon substitution mutations as a method that can be used to generate candidate vaccine viruses with increased genetic stability and/or a modified level of attenuation.
Protection of
Penaeus monodon
against White Spot Syndrome Virus by Oral Vaccination
Authors: Witteveldt Jeroen , Cifuentes Carolina C. , Vlak Just M. , van Hulten Mariëlle C. W. 
Published: January 2004

ABSTRACT

White spot syndrome virus (WSSV) occurs worldwide and causes high mortality and considerable economic damage to the shrimp farming industry. No adequate treatments against this virus are available. It is generally accepted that invertebrates such as shrimp do not have an adaptive immune response system such as that present in vertebrates. As it has been demonstrated that shrimp surviving a WSSV infection have higher survival rates upon subsequent rechallenge, we investigated the potential of oral vaccination of shrimp with subunit vaccines consisting of WSSV virion envelope proteins.
Penaeus monodon
shrimp were fed food pellets coated with inactivated bacteria overexpressing two WSSV envelope proteins, VP19 and VP28. Vaccination with VP28 showed a significant lower cumulative mortality compared to vaccination with bacteria expressing the empty vectors after challenge via immersion (relative survival, 61%), while vaccination with VP19 provided no protection. To determine the onset and duration of protection, challenges were subsequently performed 3, 7, and 21 days after vaccination. A significantly higher survival was observed both 3 and 7 days postvaccination (relative survival, 64% and 77%, respectively), but the protection was reduced 21 days after the vaccination (relative survival, 29%). This suggests that contrary to current assumptions that invertebrates do not have a true adaptive immune system, a specific immune response and protection can be induced in
P. monodon
. These experiments open up new ways to benefit the WSSV-hampered shrimp farming industry.
Development of a GB Virus B Marmoset Model and Its Validation with a Novel Series of Hepatitis C Virus NS3 Protease Inhibitors
Authors: Bright Helen , Carroll Anthony R. , Watts Paul A. , Fenton Robert J. 
Published: January 2004

ABSTRACT

GB virus B (GBV-B), a flavivirus closely related to HCV, has previously been shown to infect and replicate to high titers in tamarins (
Saguinus
sp.). This study describes the use of GBV-B infection and replication in the common marmoset (
Callithrix jacchus
) for the successful development and validation of a surrogate animal model for hepatitis C virus (HCV). Infection of marmosets with GBV-B produced a viremia that peaked at 10
8
to 10
9
genome copies/ml for a period of 40 to 60 days followed by viral clearance at 60 to 80 days postinfection. Passage of the initial tamarin-derived GBV-B in marmosets produced an infectious stock that gave a more reproducible and consistent infection in the marmoset. Titration of the virus stocks in vivo indicated that they contained 1 infectious unit for every 1,000 genome copies. Cultures of primary marmoset hepatocytes were also successfully infected with GBV-B, with high levels of virus detected in supernatants and cells for up to 14 days postinfection. Treatment of GBV-B-infected hepatocyte cultures with a novel class of HCV protease inhibitor (pyrrolidine 5,5
trans
-lactams) reduced viral levels by more than 2 logs. Treatment of GBV-B-infected marmosets with one such inhibitor resulted in a 3-log drop in serum viral titer over 4 days of therapy. These studies provide the first demonstration of the in vivo efficacy of a small-molecule inhibitor for HCV in an animal model and illustrate the utility of GBV-B as a surrogate animal model system for HCV.
Influence of Primate Lentiviral Vif and Proteasome Inhibitors on Human Immunodeficiency Virus Type 1 Virion Packaging of APOBEC3G
Authors: Liu Bindong , Yu Xianghui , Luo Kun , Yu Yunkai , Yu Xiao-Fang 
Published: January 2004

ABSTRACT
The Vif protein of human immunodeficiency virus type 1 (HIV-1) is essential for viral evasion of the host antiviral protein APOBEC3G, also known as CEM15. Vif mutant but not wild-type HIV-1 viruses produced in the presence of APOBEC3G have been shown to undergo hypermutations in newly synthesized viral DNA upon infection of target cells, presumably resulting from C-to-U modification during minus-strand viral DNA synthesis. We now report that HIV-1 Vif could induce rapid degradation of human APOBEC3G that was blocked by the proteasome inhibitor MG132. The efficiency of Vif-induced downregulation of APOBEC3G expression depended on the level of Vif expression. A single amino acid substitution in the conserved SLQXLA motif reduced Vif function. Vif proteins from distantly related primate lentiviruses such as SIVagm were unable to suppress the antiviral activity of human APOBEC3G or the packaging of APOBEC3G into HIV-1 Vif mutant virions, due to a lack of interaction with human APOBEC3G. In the presence of the proteasome inhibitor MG132, virion-associated Vif increased dramatically. However, increased virion packaging of Vif did not prevent virion packaging of APOBEC3G when proteasome function was impaired, and the infectivity of these virions was significantly reduced. These results suggest that Vif function is required during virus assembly to remove APOBEC3G from packaging into released virions. Once packaged, virion-associated Vif could not efficiently block the antiviral activity of APOBEC3G.
The Human Immunodeficiency Virus Type 1 Ribosomal Frameshifting Site Is an Invariant Sequence Determinant and an Important Target for Antiviral Therapy
Authors: Biswas Preetha , Jiang Xi , Pacchia Annmarie L. , Dougherty Joseph P. , Peltz Stuart W. 
Published: January 2004

ABSTRACT
Human immunodeficiency virus type 1 (HIV-1) utilizes a distinctive form of gene regulation as part of its life cycle, termed programmed −1 ribosomal frameshifting, to produce the required ratio of the Gag and Gag-Pol polyproteins. We carried out a sequence comparison of 1,000 HIV-1 sequences at the slippery site (UUUUUUA) and found that the site is invariant, which is somewhat surprising for a virus known for its variability. This prompted us to prepare a series of mutations to examine their effect upon frameshifting and viral infectivity. Among the series of mutations were changes of the HIV-1 slippery site to those effectively utilized by other viruses, because such mutations would be anticipated to have a relatively mild effect upon frameshifting. The results demonstrate that any change to the slippery site reduced frameshifting levels and also dramatically inhibited infectivity. Because ribosomal frameshifting is essential for HIV-1 replication and it is surprisingly resistant to mutation, modulation of HIV-1 frameshifting efficiency potentially represents an important target for the development of novel antiviral therapeutics.
Mutant PrP
Sc
Conformers Induced by a Synthetic Peptide and Several Prion Strains
Authors: Tremblay Patrick , Ball Haydn L. , Kaneko Kiyotoshi , Groth Darlene , Hegde Ramanujan S. , Cohen Fred E. , DeArmond Stephen J. , Prusiner Stanley B. , Safar Jiri G. 
Published: January 2004

ABSTRACT

Gerstmann-Sträussler-Scheinker (GSS) disease is a dominantly inherited, human prion disease caused by a mutation in the prion protein (PrP) gene. One mutation causing GSS is P102L, denoted P101L in mouse PrP (MoPrP). In a line of transgenic mice denoted Tg2866, the P101L mutation in MoPrP produced neurodegeneration when expressed at high levels. MoPrP
Sc
(P101L) was detected both by the conformation-dependent immunoassay and after protease digestion at 4°C. Transmission of prions from the brains of Tg2866 mice to those of Tg196 mice expressing low levels of MoPrP(P101L) was accompanied by accumulation of protease-resistant MoPrP
Sc
(P101L) that had previously escaped detection due to its low concentration. This conformer exhibited characteristics similar to those found in brain tissue from GSS patients. Earlier, we demonstrated that a synthetic peptide harboring the P101L mutation and folded into a β-rich conformation initiates GSS in Tg196 mice (29). Here we report that this peptide-induced disease can be serially passaged in Tg196 mice and that the PrP conformers accompanying disease progression are conformationally indistinguishable from MoPrP
Sc
(P101L) found in Tg2866 mice developing spontaneous prion disease. In contrast to GSS prions, the 301V, RML, and 139A prion strains produced large amounts of protease-resistant PrP
Sc
in the brains of Tg196 mice. Our results argue that MoPrP
Sc
(P101L) may exist in at least several different conformations, each of which is biologically active. Such conformations occurred spontaneously in Tg2866 mice expressing high levels of MoPrP
C
(P101L) as well as in Tg196 mice expressing low levels of MoPrP
C
(P101L) that were inoculated with brain extracts from ill Tg2866 mice, with a synthetic peptide with the P101L mutation and folded into a β-rich structure, or with prions recovered from sheep with scrapie or cattle with bovine spongiform encephalopathy.
Analysis of Chromatin Attachment and Partitioning Functions of Bovine Papillomavirus Type 1 E2 Protein
Authors: Abroi Aare , Ilves Ivar , Kivi Sirje , Ustav Mart 
Published: January 2004

ABSTRACT
Recent studies have suggested that the tethering of viral genomes to host cell chromosomes could provide one of the ways to achieve their nuclear retention and partitioning during extrachromosomal maintenance in dividing cells. The data we present here provide firm evidence that the partitioning of the bovine papillomavirus type 1 (BPV1) genome is dependent on the chromatin attachment process mediated by viral E2 protein and its multiple binding sites. On the other hand, the attachment of E2 and the E2-mediated tethering of reporter plasmids to host chromosomes are not necessarily sufficient for efficient partitioning, suggesting that additional E2-dependent activities might be involved in the latter process. The activity of E2 protein in chromatin attachment and partitioning is more sensitive to the point mutations in the N-terminal domain than its transactivation and replication initiation functions. Therefore, at least part of the interactions of the E2 N-terminal domain with its targets during the chromatin attachment and partitioning processes are likely to involve specific receptors not involved in transactivation and replication activities of the protein. The mutational analysis also indicates that the binding of E2 to chromatin is not achieved through interaction of linear N-terminal subsequences of the E2 protein with putative receptors. Instead, the composite surface elements of the N-terminal domain build up the receptor-binding surface of E2. In this regard, the interaction of BPV1 E2 with its chromosomal targets clearly differs from the interactions of LANA1 protein from Kaposi's sarcoma-associated human herpesvirus and EBNA1 from Epstein-Barr virus with their specific receptors.
Evolutionary Potential of an RNA Virus
Authors: Makeyev Eugene V. , Bamford Dennis H. 
Published: January 2004

ABSTRACT

RNA viruses are remarkably adaptable to changing environments. This is medically important because it enables pathogenic viruses to escape the immune response and chemotherapy and is of considerable theoretical interest since it allows the investigation of evolutionary processes within convenient time scales. A number of earlier studies have addressed the dynamics of adapting RNA virus populations. However, it has been difficult to monitor the trajectory of molecular changes in RNA genomes in response to selective pressures. To address the problem, we developed a novel in vitro evolution system based on a recombinant double-stranded RNA bacteriophage, φ6, containing a β-lactamase (
bla
) gene marker. Carrier-state bacterial cells are resistant to ampicillin, and after several passages, they become resistant to high concentrations of another β-lactam antibiotic, cefotaxime, due to mutations in the virus-borne
bla
gene. We monitored the changes in
bla
cDNAs induced by cefotaxime selection and observed an initial explosion in sequence variants with multiple mutations throughout the gene. After four passages, a stable, homogeneous population of
bla
sequences containing three specific nonsynonymous mutations was established. Of these, two mutations (E104K and G238S) have been previously reported for β-lactamases from cefotaxime-resistant bacterial isolates. These results extend our understanding of the molecular mechanisms of viral adaptation and also demonstrate the possibility of using an RNA virus as a vehicle for directed evolution of heterologous proteins.
Induction of Simian AIDS in Infant Rhesus Macaques Infected with CCR5- or CXCR4-Utilizing Simian-Human Immunodeficiency Viruses Is Associated with Distinct Lesions of the Thymus
Authors: Reyes R. A. , Canfield Don R. , Esser Ursula , Adamson Lourdes A. , Brown Charles R. , Cheng-Mayer Cecilia , Gardner Murray B. , Harouse Janet M. , Luciw Paul A. 
Published: January 2004

ABSTRACTNewborn rhesus macaques were infected with two chimeric simian-human immunodeficiency virus (SHIV) strains which contain unique human immunodeficiency virus type 1 (HIV-1)envgenes and exhibit distinct phenotypes. Infection with either the CCR5-specific SHIVSF162P3or the CXCR4-utilizing SHIVSF33Aresulted in clinical manifestations consistent with simian AIDS. Most prominent in this study was the detection of severe thymic involution in all SHIVSF33A-infected infants, which is very similar to HIV-1-induced thymic dysfunction in children who exhibit a rapid pattern of disease progression. In contrast, SHIVSF162P3induced only a minor disruption in thymic morphology. Consistent with the distribution of the coreceptors CXCR4 and CCR5 within the thymus, the expression of SHIVSF162P3was restricted to the thymic medulla, whereas SHIVSF33Awas preferentially detected in the cortex. This dichotomy of tissue tropism is similar to the differential tropism of HIV-1 isolates observed in the reconstituted human thymus in SCID-hu mice. Accordingly, our results show that the SHIV-monkey model can be used for the molecular dissection of cell and tissue tropisms controlled by the HIV-1envgene and for the analysis of mechanisms of viral immunopathogenesis in AIDS. Furthermore, these findings could help explain the rapid progression of disease observed in some HIV-1-infected children.
Distribution of Hydrophobic Residues Is Crucial for the Fusogenic Properties of the Ebola Virus GP2 Fusion Peptide
Authors: Adam B. , Lins L. , Stroobant V. , Thomas A. , Brasseur R. 
Published: January 2004

ABSTRACT
The lipid-destabilizing properties of the N-terminal domain of the GP2 of Ebola virus were investigated. Our results suggest that the domain of Ebola virus needed for fusion is shorter than that previously reported. The fusogenic properties of this domain are related to its oblique orientation at the lipid/water interface owing to an asymmetric distribution of the hydrophobic residues when helical.
Antiviral Activity of Distamycin A against Vaccinia Virus Is the Result of Inhibition of Postreplicative mRNA Synthesis
Authors: Broyles Steven S. , Kremer Marcia , Knutson Bruce A. 
Published: January 2004

ABSTRACT
Distamycin A has been described as an inhibitor of the cellular pathogenesis of vaccinia virus in culture. Distamycin is an antibiotic that specifically targets the minor groove of DNA. We show here that distamycin is a potent inhibitor of vaccinia virus replication. Pulse-labeling experiments showed that most major late proteins failed to accumulate in the presence of the antibiotic. We characterized the effect of distamycin on vaccinia virus nucleic acid biosynthesis with the goal of determining the inhibitor's target. Early gene transcription was unaffected. DNA synthesis proceeded at normal rates, but DNA accumulated in large masses in the cytoplasm with no evidence of virion assembly. Transcription from the intermediate class promoter for the I1L gene was partially reduced by distamycin; however, transcription from the intermediate promoters for the three late transcription factor genes was severely inhibited. The accumulation of the late transcripts for the viral F17R and A10L genes also was severely impaired and was shown to be a direct inhibition of late promoter activity. These results indicate that inhibition of postreplicative intermediate and late transcription is the basis for inhibition of vaccinia virus by distamycin and indicate that DNA minor-groove ligands hold promise for effective anti-poxvirus drugs.
The Viral E4 Protein Is Required for the Completion of the Cottontail Rabbit Papillomavirus Productive Cycle In Vivo
Authors: Peh Woei L. , Brandsma Janet L. , Christensen Neil D. , Cladel Nancy M. , Wu Xing , Doorbar John 
Published: January 2004

ABSTRACT
Expression of the papillomavirus E4 protein correlates with the onset of viral DNA amplification. Using a mutant cottontail rabbit papillomavirus (CRPV) genome incapable of expressing the viral E4 protein, we have shown that E4 is required for the productive stage of the CRPV life cycle in New Zealand White and cottontail rabbits. In these lesions, E4 was not required for papilloma development, but the onset of viral DNA amplification and L1 expression were abolished. Viral genome amplification was partially restored when mutant genomes able to express longer forms of E4 were used. These findings suggest that efficient amplification of the CRPV genome is dependent on the expression of a full-length CRPV E4 protein.
Phylogenetic Analyses of Texas Isolates Indicate an Evolving Subtype of the Clade B Feline Immunodeficiency Viruses
Authors: Weaver Eric A. , Collisson Ellen W. , Slater Margaret , Zhu Guan 
Published: January 2004

ABSTRACT
Rigorous phylogenetic analyses were used to compare the nucleotide sequences of feline immunodeficiency virus strains isolated from Texas and throughout the world. The envelope V3-V4 sequences and capsid gene of the Texas isolates formed a cluster between subtypes B and E. Statistical comparisons with other published sequences confirmed that the Texas group is a unique cluster, possibly a new subtype, arising from subtype B.
On the Structure and Physical Origin of the Weak Interaction Between H and CO
Authors: Lukeš Vladimír , Laurinc Viliam , Ilčin Michal , Biskupič Stanislav 
Published: January 2004

The adiabatic potential energy surface of the H-CO complex in the van der Waals region, described by Jacobi coordinates (r = 1.128 Å, R, Θ), was investigated using the supermolecular coupled-clusters CCSD(T) method. Our calculations indicate a minimum for bent arrangements. It was found on the carbon side of CO molecule at R = 3.6 Å (Θ = 76°) with a well depth of De = -156.5 μEh. The saddle points are localised at linear conformations for R = 4.37 Å (Θ = 0°) and R = 3.91 Å (Θ = 180°). The physical origin of the studied interaction was analysed by the intermolecular perturbation theory based on the single-determinant unrestricted Hartree-Fock wave function. The separation of the interaction energies shows that the locations of the predicted stable bent structure is primarily determined by delicate balance between the repulsive Heitler-London and attractive dispersion and induction energy components.
The Infrared Spectrum of CN in Its Ground Electronic State
Authors: Horká Veronika , Civiš Svatopluk , Špirko Vladimír , Kawaguchi Kentarou 
Published: January 2004

12C14N vibration-rotation bands for the sequences (1-0) through (9-8) were observed in the spectral region 1800-2200 cm-1 using a Bruker 120 HR Fourier transform spectrometer at an unapodized resolution of 0.027 cm-1. Of the 362 lines observed, the wavenumbers of 237 lines were least-squares fitted using the Dunham expansion coefficients with a root-mean-square deviation of 0.00093 cm-1. Together with most accurate data from the literature, the data were also fitted in the framework of the reduced potential curve (RPC) method. The global potential energy function resulting from this fit provides a fairly quantitative description of the experimental data, at least up to 30 000 cm-1. In addition to global fitting, the RPC approach was also used for fully quantitative fitting of the data pertaining to the lowest three vibrational states. The effective potential energy curves obtained in this way allow for very accurate predictions of highly excited rotational states.
The immunohistochemical localisation of somatostatin receptors 1, 2, 3, and 5 in acoustic neuromas
Authors: Stafford N D , Condon L T , Rogers M J C , Helboe L , Crooks D A , Atkin S L 
Published: January 2004

Aims:Acoustic neuroma is a benign tumour, which develops through an overproliferation of Schwann cells along the vestibular nerve. Somatostatin is a naturally occurring peptide, which exerts antiproliferative and antiangiogenic effects via five membrane bound receptor subtypes. The aim of this study was to determine whether somatostatin receptor subtypes (SSTRs) 1, 2, 3, and 5 are present in acoustic neuromas.Methods:The expression of SSTRs 1, 2, 3, and 5 was studied in both the Schwann cells and blood vessels of eight acoustic neuroma specimens, by means of immunohistochemistry using novel rabbit polyclonal antibodies raised against human SSTR 1, 2, and 5 subtype specific peptides, and a commercial anti-SSTR3 antibody.Results:SSTR2 was the most prevalent subtype in Schwann cells (seven of eight), with intermediate expression of SSTR3 (six of eight), and lower expression of SSTRs 1 and 5 (four of eight and five of eight, respectively). There was ubiquitous vascular expression of SSTR2, with no evidence of SSTR 1, 3, or 5 expression in blood vessels.Conclusion:SSTRs 1, 2, 3, and 5 are differentially expressed in acoustic neuromas. Somatostatin analogues may have a therapeutic role in the management of this rare and challenging condition.