bluuebunny/crossref_metadata_2025_split huggingface dataset:
Demyelination Determinants Map to the Spike Glycoprotein Gene of Coronavirus Mouse Hepatitis Virus
Authors: Das Sarma Jayasri , Fu Li , Tsai Jean C. , Weiss Susan R. , Lavi Ehud 
Published: July 2002

ABSTRACTDemyelination is the pathologic hallmark of the human immune-mediated neurologic disease multiple sclerosis, which may be triggered or exacerbated by viral infections. Several experimental animal models have been developed to study the mechanism of virus-induced demyelination, including coronavirus mouse hepatitis virus (MHV) infection in mice. The envelope spike (S) glycoprotein of MHV contains determinants of properties essential for virus-host interactions. However, the molecular determinants of MHV-induced demyelination are still unknown. To investigate the mechanism of MHV-induced demyelination, we examined whether the S gene of MHV contains determinants of demyelination and whether demyelination is linked to viral persistence. Using targeted RNA recombination, we replaced the S gene of a demyelinating virus (MHV-A59) with the S gene of a closely related, nondemyelinating virus (MHV-2). Recombinant viruses containing an S gene derived from MHV-2 in an MHV-A59 background (Penn98-1 and Penn98-2) exhibited a persistence-positive, demyelination-negative phenotype. Thus, determinants of demyelination map to the S gene of MHV. Furthermore, viral persistence is insufficient to induce demyelination, although it may be a prerequisite for the development of demyelination.
Isolation and Characterization of H4N6 Avian Influenza Viruses from Pigs with Pneumonia in Canada
Authors: Karasin Alexander I. , Brown Ian H. , Carman Suzanne , Olsen Christopher W. 
Published: July 2002

ABSTRACT
In October 1999, H4N6 influenza A viruses were isolated from pigs with pneumonia on a commercial swine farm in Canada. Phylogenetic analyses of the sequences of all eight viral RNA segments demonstrated that these are wholly avian influenza viruses of the North American lineage. To our knowledge, this is the first report of interspecies transmission of an avian H4 influenza virus to domestic pigs under natural conditions.
Unusual Distribution of Mutations Associated with Serial Bottleneck Passages of Human Immunodeficiency Virus Type 1
Authors: Yuste Eloisa , López-Galíndez Cecilio , Domingo Esteban 
Published: July 2002

ABSTRACTRepeated bottleneck passages result in fitness losses of RNA viruses. In the case of human immunodeficiency virus type 1 (HIV-1), decreases in fitness after a limited number of plaque-to-plaque transfers in MT-4 cells were very drastic. Here we report an analysis of entire genomic nucleotide sequences of four HIV-1 clones derived from the same HIV-1 isolate and their low-fitness progeny following 7 to 15 plaque-to-plaque passages. Clones accumulated 4 to 28 mutations per genome, with dominance of A → G and G → A transitions (57% of all mutations) and 49% nonsynonymous replacements. One clone—but not three sibling clones—showed an overabundance of G → A transitions, evidencing the highly stochastic nature of some types of mutational bias. The distribution of mutations along the genome was very unusual in that mutation frequencies ingagwere threefold higher than inenv. Particularly striking was the complete absence of replacements in the V3 loop of gp120, confirmed with partial nucleotide sequences of additional HIV-1 clones subjected to repeated bottleneck passages. The analyses revealed several amino acid replacements that have not been previously recorded among natural HIV-1 isolates and illustrate how evolution of an RNA virus genome, with regard to constant and variable regions, can be profoundly modified by alterations in population dynamics.
Three-Dimensional Structure of the Human Herpesvirus 8 Capsid
Authors: Wu Lijun , Lo Pierrette , Yu Xuekui , Stoops James K. , Forghani B. , Zhou Z. Hong 
Published: July 2002

ABSTRACT

Human herpesvirus 8 (HHV-8), or Kaposi's sarcoma-associated herpesvirus, is a gammaherpesvirus implicated in all forms of Kaposi's sarcoma and certain lymphomas. HHV-8 has been extensively characterized, both biochemically and immunologically, since its first description in 1994. However, its three-dimensional (3D) structure remained heretofore undetermined largely due to difficulties in viral purification. We have used log-phase cultures of body cavity-based lymphoma 1 cells induced with 12-
O
-tetradecanoylphorbol-13-acetate to obtain HHV-8 capsids for electron cryomicroscopy and computer reconstruction. The 3D structure of the HHV-8 capsids revealed a capsid shell composed of 12 pentons, 150 hexons, and 320 triplexes arranged on a T=16 icosahedral lattice. This structure is similar to those of herpes simplex virus type 1 (HSV-1) and human cytomegalovirus (HCMV), which are prototypical members of alpha- and betaherpesviruses, respectively. The inner radius of the HHV-8 capsid is identical to that of the HSV-1 capsid but is smaller than that of the HCMV capsid, which is consistent with the relative sizes of the genomes they enclose. While the HHV-8 capsid exhibits many structural similarities to the HSV-1 capsid, our reconstruction shows two major differences: its hexons lack the “horn-shaped” VP26 densities bound to the HSV-1 hexon subunits, and the HHV-8 triplexes appear smaller and less elongated than those of HSV-1. These differences are in excellent agreement with our sequence comparisons of HHV-8 and HSV-1 capsid proteins. This gammaherpesvirus capsid structure complements previous structural studies on alpha- and betaherpesviruses in providing an account of structural similarities and differences among capsids representing all human herpesvirus subfamilies.
Genetic and Biochemical Studies of Poliovirus
cis
-Acting Replication Element
cre
in Relation to VPg Uridylylation
Authors: Rieder Elizabeth , Paul Aniko V. , Kim Dong Wook , van Boom Jacques H. , Wimmer Eckard 
Published: July 2002

ABSTRACT

In addition to highly conserved stem-loop structures located in the 5′- and 3′-nontranslated regions, genome replication of picornaviruses requires
cis
-acting RNA elements located in the coding region (termed
cre
) (K. L. McKnight and S. M. Lemon, J. Virol. 70:1941–1952, 1996; P. E. Lobert, N. Escriou, J. Ruelle, and T. Michiels, Proc. Natl. Acad. Sci. USA 96:11560–11565, 1999; I. Goodfellow, Y. Chaudhry, A. Richardson, J. Meredith, J. W. Almond, W. Barclay, and D. J. Evans, J. Virol. 74:4590–4600, 2000).
cre
elements appear to be essential for minus-strand RNA synthesis by an as-yet-unknown mechanism. We have discovered that the
cre
element of poliovirus (mapping to the 2C coding region of poliovirus type 1; nucleotides 4444 to 4505 in 2C), which is homologous to the
cre
element of poliovirus type 3, is preferentially used as a template for the in vitro uridylylation of VPg catalyzed by 3D
pol
in a reaction that is greatly stimulated by 3CD
pro
(A. V. Paul, E. Rieder, D. W. Kim, J. H. van Boom, and E. Wimmer, J. Virol. 74:10359–10370, 2000). Here we report a direct correlation between mutations that eliminate, or severely reduce, the in vitro VPg-uridylylation reaction and produce replication phenotypes in vivo. None of the genetic changes significantly influenced translation or polyprotein processing. A substitution mapping to the first A (A4472C) of a conserved
A
AACA sequence in the loop of PV-
cre
(2C) eliminated the ability of the
cre
RNA to serve as template for VPg uridylylation and abolished RNA infectivity. Mutagenesis of the second A (A4473C; A
A
ACA) severely reduced the yield of VPgpUpU and RNA infectivity was restored only after reversion to the wild-type sequence. The effect of substitution of the third A (A4474G; AA
A
CA) was less severe but reduced both VPg uridylylation and virus yield. Disruption of base pairing within the upper stem region of PV-
cre
(2C) also affected uridylylation of VPg. Virus derived from transcripts containing mutations in the stem was either viable or quasi-infectious.
Identification and Functional Analysis of the Turnip Yellow Mosaic Tymovirus Subgenomic Promoter
Authors: Schirawski Jan , Voyatzakis Ariane , Zaccomer Bruno , Bernardi Françoise , Haenni Anne-Lise 
Published: July 2002

ABSTRACT
Most plant viruses rely on the production of subgenomic RNAs (sgRNAs) for the expression of their genes and survival in the plant. Although this is a widely adopted strategy among viruses, the mechanism(s) whereby sgRNA production occurs remains poorly defined. Turnip yellow mosaic tymovirus (TYMV) is a positive-stranded RNA virus that produces an sgRNA for the expression of its coat protein. Here we report that the subgenomic promoter sequence of TYMV is located on a 494-nucleotide fragment, containing previously identified highly conserved sequence elements, which are shown here to be essential for promoter function. After duplication, the subgenomic promoter can be inserted into the coat protein open reading frame, giving rise to the in vivo production of a second sgRNA. It is suggested that this promoter can function when contained on a different molecule than viral genomic RNA. This interesting trait may be of general use for plant and plant virus research.
Canarypox Virus-Induced Maturation of Dendritic Cells Is Mediated by Apoptotic Cell Death and Tumor Necrosis Factor Alpha Secretion
Authors: Ignatius Ralf , Marovich Mary , Mehlhop Erin , Villamide Loreley , Mahnke Karsten , Cox William I. , Isdell Frank , Frankel Sarah S. , Mascola John R. , Steinman Ralph M. , Pope Melissa 
Published: July 2002

ABSTRACTRecombinant avipox viruses are being widely evaluated as vaccines. To address how these viruses, which replicate poorly in mammalian cells, might be immunogenic, we studied how canarypox virus (ALVAC) interacts with primate antigen-presenting dendritic cells (DCs). When human and rhesus macaque monocyte-derived DCs were exposed to recombinant ALVAC, immature DCs were most susceptible to infection. However, many of the infected cells underwent apoptotic cell death, and dying infected cells were engulfed by uninfected DCs. Furthermore, a subset of DCs matured in the ALVAC-exposed DC cultures. DC maturation coincided with tumor necrosis factor alpha (TNF-α) secretion and was significantly blocked in the presence of anti-TNF-α antibodies. Interestingly, inhibition of apoptosis with a caspase 3 inhibitor also reduced some of the maturation induced by exposure to ALVAC. This indicates that both TNF-α and the presence of primarily apoptotic cells contributed to DC maturation. Therefore, infection of immature primate DCs with ALVAC results in apoptotic death of infected cells, which can be internalized by noninfected DCs driving DC maturation in the presence of the TNF-α secreted concomitantly by exposed cells. This suggests an important mechanism that may influence the immunogenicity of avipox virus vectors.
The Herpes Simplex Virus 1 U
L
34 Protein Interacts with a Cytoplasmic Dynein Intermediate Chain and Targets Nuclear Membrane
Authors: Ye Guo-Jie , Vaughan Kevin T. , Vallee Richard B. , Roizman Bernard 
Published: July 2002

ABSTRACT

To express the function encoded in its genome, the herpes simplex virus 1 capsid-tegument structure released by deenvelopment during entry into cells must be transported retrograde to the nuclear pore where viral DNA is released into the nucleus. This path is essential in the case of virus entering axons of dorsal root ganglia. The objective of the study was to identify the viral proteins that may be involved in the transport. We report the following findings. (i) The neuronal isoform of the intermediate chain (IC-1a) of the dynein complex pulled down, from lysates of [
35
S]methionine-labeled infected cells, two viral proteins identified as the products of U
L
34 and U
L
31 open reading frames, respectively. U
L
34 protein is a virion protein associated with cellular membranes and phosphorylated by the viral kinase U
S
3. U
L
31 protein is a largely insoluble, evenly dispersed nuclear phosphoprotein required for optimal processing and packaging of viral DNA into preformed capsids. Reciprocal pulldown experiments verified the interaction of IC-1a and U
L
34 protein. In similar experiments, U
L
34 protein was found to interact with U
L
31 protein and the major capsid protein ICP5. (ii) To determine whether U
L
34 protein is transported to the nuclear membrane, a requirement if it is involved in transport, the U
L
34 protein was inserted into a baculovirus vector under the cytomegalovirus major early promoter. Cells infected with the recombinant baculovirus expressed U
L
34 protein in a dose-dependent manner, and the U
L
34 protein localized primarily in the nuclear membrane. An unexpected finding was that U
L
34-expressing cells showed a dissociation of the inner and outer nuclear membranes reminiscent of the morphologic changes seen in cells productively infected with herpes simplex virus 1. U
L
34, like many other viral proteins, may have multiple functions expressed both early and late in infection.
Role of the Influenza Virus M1 Protein in Nuclear Export of Viral Ribonucleoproteins
Authors: Bui Matthew , Wills Elizabeth G. , Helenius Ari , Whittaker Gary R. 
Published: July 2002

ABSTRACT
The protein kinase inhibitor H7 blocks influenza virus replication, inhibits production of the matrix protein (M1), and leads to a retention of the viral ribonucleoproteins (vRNPs) in the nucleus at late times of infection (K. Martin and A. Helenius, Cell 67:117–130, 1991). We show here that production of assembled vRNPs occurs normally in H7-treated cells, and we have used H7 as a biochemical tool to trap vRNPs in the nucleus. When H7 was removed from the cells, vRNP export was specifically induced in a CHO cell line stably expressing recombinant M1. Similarly, fusion of cells expressing recombinant M1 from a Semliki Forest virus vector allowed nuclear export of vRNPs. However, export was not rescued when H7 was present in the cells, implying an additional role for phosphorylation in this process. The viral NS2 protein was undetectable in these systems. We conclude that influenza virus M1 is required to induce vRNP nuclear export but that cellular phosphorylation is an additional factor.
Efficient Gene Transfer into Human CD34
+
Cells by a Retargeted Adenovirus Vector
Authors: Shayakhmetov Dmitry M. , Papayannopoulou Thalia , Stamatoyannopoulos George , Lieber André 
Published: July 2002

ABSTRACT

Efficient infection with adenovirus (Ad) vectors based on serotype 5 (Ad5) requires the presence of coxsackievirus-adenovirus receptors (CAR) and α
v
integrins on cells. The paucity of these cellular receptors is thought to be a limiting factor for Ad gene transfer into hematopoietic stem cells. In a systematic approach, we screened different Ad serotypes for interaction with noncycling human CD34
+
cells and K562 cells on the level of virus attachment, internalization, and replication. From these studies, serotype 35 emerged as the variant with the highest tropism for CD34
+
cells. A chimeric vector (Ad5GFP/F35) was generated which contained the short-shafted Ad35 fiber incorporated into an Ad5 capsid. This substitution was sufficient to transplant all infection properties from Ad35 to the chimeric vector. The retargeted, chimeric vector attached to a receptor different from CAR and entered cells by an α
v
integrin-independent pathway. In transduction studies, Ad5GFP/F35 expressed green fluorescent protein (GFP) in 54% of CD34
+
cells. In comparison, the standard Ad5GFP vector conferred GFP expression to only 25% of CD34
+
cells. Importantly, Ad5GFP transduction, but not Ad5GFP/F35, was restricted to a specific subset of CD34
+
cells expressing α
v
integrins. The actual transduction efficiency was even higher than 50% because Ad5GFP/F35 viral genomes were found in GFP-negative CD34
+
cell fractions, indicating that the cytomegalovirus promoter used for transgene expression was not active in all transduced cells. The chimeric vector allowed for gene transfer into a broader spectrum of CD34
+
cells, including subsets with potential stem cell capacity. Fifty-five percent of CD34
+
c-Kit
+
cells expressed GFP after infection with Ad5GFP/F35, whereas only 13% of CD34
+
c-Kit
+
cells were GFP positive after infection with Ad5GFP. These findings represent the basis for studies aimed toward stable gene transfer into hematopoietic stem cells.
Diminishing Returns of Population Size in the Rate of RNA Virus Adaptation
Authors: Miralles Rosario , Moya Andrés , Elena Santiago F. 
Published: July 2002

ABSTRACT
Whenever an asexual viral population evolves by adapting to new environmental conditions, beneficial mutations, the ultimate cause of adaptation, are randomly produced and then fixed in the population. The larger the population size and the higher the mutation rate, the more beneficial mutations can be produced per unit time. With the usually high mutation rate of RNA viruses and in a large enough population, several beneficial mutations could arise at the same time but in different genetic backgrounds, and if the virus is asexual, they will never be brought together through recombination. Thus, the best of these genotypes must outcompete each other on their way to fixation. This competition among beneficial mutations has the effect of slowing the overall rate of adaptation. This phenomenon is known as clonal interference. Clonal interference predicts a speed limit for adaptation as the population size increases. In the present report, by varying the size of evolving vesicular stomatitis virus populations, we found evidence clearly demonstrating this speed limit and thus indicating that clonal interference might be an important factor modulating the rate of adaptation to an in vitro cell system. Several evolutionary and epidemiological implications of the clonal interference model applied to RNA viruses are discussed.
Establishment of Monoclonal Anti-Retroviral gp70 Autoantibodies from MRL/lprLupus Mice and Induction of Glomerular gp70 Deposition and Pathology by Transfer into Non-Autoimmune Mice
Authors: Tabata Nobutada , Miyazawa Masaaki , Fujisawa Ryuichi , Takei Yumiko A. , Abe Hiroyuki , Hashimoto Keiji 
Published: July 2002

ABSTRACTSeveral strains of mice, including MRL/MpJ mice homozygous for the Fas mutantlprgene (MRL/lprmice), F1hybrids of New Zealand Black and New Zealand White mice, and BXSB/MpJ mice carrying a Y-linked autoimmune acceleration gene, spontaneously develop immune complex-mediated glomerulonephritis. The involvement of the envelope glycoprotein gp70 of an endogenous xenotropic virus in the formation of circulating immune complexes and their deposition in the glomerular lesions have been demonstrated, as has the pathogenicity of various antinuclear, antiphospholipid, and rheumatoid factor autoantibodies. In recent genetic linkage studies as well as in a study of cytokine-induced protection against nephritis development, the strongest association of serum levels of gp70–anti-gp70 immune complexes, rather than the levels of antinuclear autoantibodies, with the development and severity of glomerulonephritis has been demonstrated, suggesting a major pathogenic role of anti-gp70 autoantibodies in the lupus-prone mice. However, the pathogenicity of anti-gp70 autoantibodies has not yet been directly tested. To examine if anti-gp70 autoantibodies induce glomerular pathology, we established from unmanipulated MRL/lprmice hybridoma clones that secrete monoclonal antibodies reactive with endogenous xenotropic viralenvgene products. Upon transplantation, a high proportion of these anti-gp70 antibody-producing hybridoma clones induced in syngeneic non-autoimmune and severe combined immunodeficiency mice proliferative or wire loop-like glomerular lesions. Furthermore, deposition of gp70 in glomeruli and pathological changes were observed after intravenous injection of representative clones of purified anti-gp70 immunoglobulin G, demonstrating pathogenicity of at least some anti-gp70 autoantibodies.
Efficient Infection of Primary Tupaia Hepatocytes with Purified Human and Woolly Monkey Hepatitis B Virus
Authors: Köck Josef , Nassal Michael , MacNelly Sabine , Baumert Thomas F. , Blum Hubert E. , von Weizsäcker Fritz 
Published: July 2002

ABSTRACTThe Asian tree shrew,Tupaia belangeri, has been proposed as a novel animal model for studying hepatitis B virus (HBV) infection. Here, we describe a protocol for efficient and reproducible infection of primary tupaia hepatocytes with HBV. We report that human serum interferes with HBV binding to the hepatocytes, thus limiting the maximum multiplicity of infection. Purification of HBV virions by gradient sedimentation greatly enhances virus binding and infectivity. Covalently closed circular DNA was clearly detectable by Southern blot analysis and newly synthesized single-stranded HBV DNA was visible 2 weeks postinoculation. Primary tupaia hepatocytes are also susceptible to infection with the recently discovered woolly monkey hepatitis B virus (WMHBV) but not to woodchuck hepatitis virus infection. Compared to HBV, WMHBV replicated at a higher rate with single-stranded DNA detectable within the first week postinoculation. Primary tupaia hepatocytes should represent a useful system for studying early steps of HBV and WMHBV infection.
Transfer of Hepatitis B Virus Genome by Adenovirus Vectors into Cultured Cells and Mice: Crossing the Species Barrier
Authors: Sprinzl Martin Franz , Oberwinkler Heike , Schaller Heinz , Protzer Ulrike 
Published: July 2002

ABSTRACTFor the study of hepatitis B virus infection, no permissive cell line or small animal is available. Stably transfected cell lines and transgenic mice which contain hepadnavirus genomes produce virus, but—unlike in natural infection—from an integrated viral transcription template. To transfer hepadnavirus genomes across the species barrier, we developed adenovirus vectors in which 1.3-fold-overlength human and duck hepatitis B virus genomes were inserted. The adenovirus-mediated genome transfer efficiently initiated hepadnavirus replication from an extrachromosomal template in established cell lines, in primary hepatocytes from various species, and in the livers of mice. Following the transfer, hepatitis B virus proteins, genomic RNA, and all replicative DNA intermediates were detected. Detection of covalently closed circular DNA in hepatoma cell lines and in primary hepatocytes indicated that an intracellular replication cycle independent from the transferred linear viral genome was established. High-titer hepatitis B virions were released into the culture medium of hepatoma cells and the various primary hepatocytes. In addition, infectious virions were secreted into the sera of mice. In conclusion, adenovirus-mediated genome transfer initiated efficient hepatitis B virus replication in cultured liver cells and in the experimental animals from an extrachromosomal template. This will allow development of small-animal systems of hepatitis B virus infection and will facilitate study of pathogenicity of wild-type and mutant viruses as well as of virus-host interaction and new therapeutic approaches.