bluuebunny/crossref_metadata_2025_split huggingface dataset:
Host Switching in
Lyssavirus
History from the Chiroptera to the Carnivora Orders
Authors: Badrane Hassan , Tordo Noël 
Published: July 2002

ABSTRACT

Lyssaviruses are unsegmented RNA viruses causing rabies. Their vectors belong to the Carnivora and Chiroptera orders. We studied 36 carnivoran and 17 chiropteran lyssaviruses representing the main genotypes and variants. We compared their genes encoding the surface glycoprotein, which is responsible for receptor recognition and membrane fusion. The glycoprotein is the main protecting antigen and bears virulence determinants. Point mutation is the main force in lyssavirus evolution, as Sawyer's test and phylogenetic analysis showed no evidence of recombination. Tests of neutrality indicated a neutral model of evolution, also supported by globally high ratios of synonymous substitutions (

d
S

) to nonsynonymous substitutions (

d
N

) (>7). Relative-rate tests suggested similar rates of evolution for all lyssavirus lineages. Therefore, the absence of recombination and similar evolutionary rates make phylogeny-based conclusions reliable. Phylogenetic reconstruction strongly supported the hypothesis that host switching occurred in the history of lyssaviruses. Indeed, lyssaviruses evolved in chiropters long before the emergence of carnivoran rabies, very likely following spillovers from bats. Using dated isolates, the average rate of evolution was estimated to be roughly 4.3 × 10
−4

d
S

/site/year. Consequently, the emergence of carnivoran rabies from chiropteran lyssaviruses was determined to have occurred 888 to 1,459 years ago. Glycoprotein segments accumulating more

d
N

than

d
S

were distinctly detected in carnivoran and chiropteran lyssaviruses. They may have contributed to the adaptation of the virus to the two distinct mammal orders. In carnivoran lyssaviruses they overlapped the main antigenic sites, II and III, whereas in chiropteran lyssaviruses they were located in regions of unknown functions.
LFA-1 Expression on Target Cells Promotes Human Immunodeficiency Virus Type 1 Infection and Transmission
Authors: Hioe Catarina E. , Chien Peter C. , Lu ChaFen , Springer Timothy A. , Wang Xiao-Hong , Bandres Juan , Tuen Michael 
Published: July 2002

ABSTRACTWhile CD4 and the chemokine receptors are the principal receptors for human immunodeficiency virus (HIV), other cellular proteins, such as LFA-1, are also involved in HIV infection. LFA-1 and its ligands, ICAM-1, ICAM-2, and ICAM-3, can be expressed on the cells infected by HIV, as well as on the HIV virions themselves. To examine the role of LFA-1 expressed on target cells in HIV infection, Jurkat-derived Jβ2.7 T-cell lines that express either wild-type LFA-1, a constitutively active mutant LFA-1, or no LFA-1 were used. The presence of wild-type LFA-1 enhanced the initial processes of HIV infection, as well as the subsequent replication and transmission from cell to cell. In contrast, the constitutively active LFA-1 mutant failed to promote virus replication and spread, even though this mutant could help HIV enter cells and establish the initial infection. This study clearly demonstrates the contribution of LFA-1 in the different stages of HIV infection. Moreover, not only is LFA-1 expression important for initial HIV-cell interaction, subsequent replication, and transmission, but its activity must also be properly regulated.
Positively Charged Termini of the L2 Minor Capsid Protein Are Necessary for Papillomavirus Infection
Authors: Roden Richard B. S. , Day Patricia M. , Bronzo Brian K. , Yutzy William H. , Yang Yanqin , Lowy Douglas R. , Schiller John T. 
Published: July 2002

ABSTRACT
Coexpression of bovine papillomavirus L1 with L2 mutants lacking either eight N-terminal or nine C-terminal amino acids that encode positively charged domains resulted in wild-type levels of viral genome encapsidation. Despite wild-type binding to the cell surface, the resulting virions were noninfectious. An L2 mutant encoding a scrambled version of the nine C-terminal residues restored infectivity, in contrast to an L2 mutant encoding a scrambled version of the N-terminal residues.
Cross-Reactivity between Hepatitis C Virus and Influenza A Virus Determinant-Specific Cytotoxic T Cells
Authors: Wedemeyer Heiner , Mizukoshi Eishiro , Davis Anthony R. , Bennink Jack R. , Rehermann Barbara 
Published: July 2002

ABSTRACTThe cellular immune response contributes to viral clearance as well as to liver injury in acute and chronic hepatitis C virus (HCV) infection. An immunodominant determinant frequently recognized by liver-infiltrating and circulating CD8+T cells of HCV-infected patients is the HCVNS3-1073peptide CVNGVCWTV. Using a sensitive in vitro technique with HCV peptides and multiple cytokines, we were able to expand cytotoxic T cells specific for this determinant not only from the blood of 11 of 20 HCV-infected patients (55%) but also from the blood of 9 of 15 HCV-negative blood donors (60%), while a second HCV NS3 determinant was recognized only by HCV-infected patients and not by seronegative controls. The T-cell response of these healthy blood donors was mediated by memory T cells, which cross-reacted with a novel T-cell determinant of the A/PR/8/34 influenza A virus (IV) that is endogenously processed from the neuraminidase (NA) protein. Both the HCV NS3 and the IV NA peptide displayed a high degree of sequence homology, bound to the HLA-A2 molecule with high affinity, and were recognized by cytotoxic T lymphocytes with similar affinity (10−8M). Using the HLA-A2-transgenic mouse model, we then demonstrated directly that HCV-specific T cells could be induced in vivo by IV infection. Splenocytes harvested from IV-infected mice at the peak of the primary response (day 7 effector cells) or following complete recovery (day 21 memory cells) recognized the HCV NS3 peptide, lysed peptide-pulsed target cells, and produced gamma interferon. These results exemplify that host responses to an infectious agent are influenced by cross-reactive memory cells induced by past exposure to heterologous viruses, which could have important consequences for vaccine development.
Identification of BV/ODV-C42, an
Autographa californica
Nucleopolyhedrovirus
orf101
-Encoded Structural Protein Detected in Infected-Cell Complexes with ODV-EC27 and p78/83
Authors: Braunagel Sharon C. , Guidry Paula A. , Rosas-Acosta German , Engelking Luke , Summers Max D. 
Published: July 2002

ABSTRACT

orf101
is a late gene of
Autographa californica
nucleopolyhedrovirus (Ac
M
NPV). It encodes a protein of 42 kDa which is a component of the nucleocapsid of budded virus (BV) and occlusion-derived virus (ODV). To reflect this viral localization, the product of
orf101
was named BV/ODV-C42 (C42). C42 is predominantly detected within the infected-cell nucleus: at 24 h postinfection (p.i.), it is coincident with the virogenic stroma, but by 72 h p.i., the stroma is minimally labeled while C42 is more uniformly located throughout the nucleus. Yeast two-hybrid screens indicate that C42 is capable of directly interacting with the viral proteins p78/83 (
1629K
) and ODV-EC27 (
orf144
). These interactions were confirmed using blue native gels and Western blot analyses. At 28 h p.i., C42 and p78/83 are detected in two complexes: one at approximately 180 kDa and a high-molecular-mass complex (500 to 600 kDa) which also contains EC27.
Partial Activation and Induction of Apoptosis in CD4+and CD8+T Lymphocytes by Conformationally Authentic Noninfectious Human Immunodeficiency Virus Type 1
Authors: Esser Mark T. , Bess Julian W. , Suryanarayana Kalachar , Chertova Elena , Marti Darlene , Carrington Mary , Arthur Larry O. , Lifson Jeffrey D. 
Published: July 2002

ABSTRACTIncreased levels of apoptosis are seen in human immunodeficiency virus (HIV) infection, and this has been proposed as an important mechanism contributing to HIV pathogenesis. However, interpretation of in vitro studies aimed at understanding HIV-related apoptosis has been complicated by the use of high concentrations of recombinant proteins or by direct cytopathic effects of replicating virus. We have developed an inactivation procedure that destroys retroviral infectivity while preserving the structural and functional integrity of the HIV surface proteins. These noninfectious virions interact authentically with target cells, providing a powerful tool to dissect mechanisms of HIV pathogenesis that do or do not require viral replication. Noninfectious CXCR4-tropic HIV-1 virions, but not microvesicles, partially activated freshly isolated CD4+and CD8+peripheral blood mononuclear cell T lymphocytes to express FasL and Fas, but not CD69 or CD25 (interleukin-2 receptor alpha) and eventually die via apoptosis starting 4 to 6 days postexposure. These effects required conformationally intact virions, as heat-denatured virions or equivalent amounts of recombinant gp120 did not induce apoptosis. The maximal apoptotic effect was dependent on major histocompatibility complex (MHC) class II proteins being present on the virion, but was not MHC restricted. The results suggest that the immunopathogenesis of HIV infection may not depend solely on direct cytopathic effects of HIV replication, but that effects due to noninfectious HIV-1 virions may also contribute importantly.
Human Immunodeficiency Virus Type 1 Nef Functions at the Level of Virus Entry by Enhancing Cytoplasmic Delivery of Virions
Authors: Schaeffer Evelyne , Geleziunas Romas , Greene Warner C. 
Published: July 2002

ABSTRACT
The Nef protein of the type 1 human immunodeficiency virus (HIV-1) plays a key although poorly understood role in accelerating the progression of clinical disease in vivo. Nef exerts several biological effects in vitro, including enhancement of virion infectivity, downregulation of CD4 and major histocompatibility complex class I receptor expression, and modulation of various intracellular signaling pathways. The positive effect of Nef on virion infectivity requires its expression in the producer cell, although its effect is manifested in the subsequent target cell of infection. Prior studies suggest that Nef does not alter viral entry into target cells; nevertheless, it enhances proviral DNA synthesis, arguing for an action of Nef at the level of viral uncoating or reverse transcription. However, these early studies discounting an effect of Nef on virion entry may be confounded by the recent finding that HIV enters cells by both fusion and endocytosis. Using epifluorescence microscopy to monitor green fluorescent protein-Vpr-labeled HIV virion entry into HeLa cells, we find that endocytosis forms a very active pathway for virus uptake. Virions entering via the endocytic pathway do not support productive infection of the host cell, presumably reflecting their inability to escape from the endosomes. Conversely, our studies now demonstrate that HIV Nef significantly enhances CD4- and chemokine receptor-dependent entry of HIV virions into the cytoplasmic compartment of target cells. Mutations in Nef either impairing its ability to downregulate CD4 or disrupting its polyproline helix compromise virion entry into the cytoplasm. We conclude that Nef acts at least in part as a regulator of cytosolic viral entry and that this action contributes to its positive effects on viral infectivity.
Characterization of Intracellular Reverse Transcription Complexes of Human Immunodeficiency Virus Type 1
Authors: Fassati Ariberto , Goff Stephen P. 
Published: July 2002

ABSTRACT
To examine the early events of the life cycle of human immunodeficiency virus type 1 (HIV-1), we analyzed the intracellular complexes mediating reverse transcription isolated from acutely infected cells. Partial purification of the reverse transcription complexes (RTCs) by equilibrium density fractionation and velocity sedimentation indicated that two species of RTCs are formed but only one species is able to synthesize DNA. Most of the capsid, matrix, and reverse transcriptase (RT) proteins dissociate from the complex soon after cell infection, but Vpr remains associated with the RTC. The RTCs isolated 1, 4, and 7 h after infection are competent for reverse transcription in vitro, indicating that a small proportion of RT remains associated with them. HIV RTCs isolated early after infection have a sedimentation velocity of approximately 560S. Later, different species with a sedimentation velocity ranging from 350S to 100S appear. Nuclear-associated RTCs have a sedimentation velocity of 80S. Shortly after initiation of reverse transcription, the viral strong-stop DNA within the RTC is sensitive to nuclease digestion and becomes protected when reverse transcription is almost completed.
Biophysical Characterization and Vector-Specific Antagonist Activity of Domain III of the Tick-Borne Flavivirus Envelope Protein
Authors: Bhardwaj S. , Holbrook M. , Shope R. E. , Barrett A. D. T. , Watowich S. J. 
Published: July 2002

ABSTRACT
The molecular determinants responsible for flavivirus host cell binding and tissue tropism are largely unknown, although domain III of the envelope protein has been implicated in these functions. We examined the solution properties and antagonist activity of Langat virus domain III. Our results suggest that domain III adopts a stably folded structure that can mediate binding of tick-borne flaviviruses but not mosquito-borne flaviviruses to their target cells. Three clusters of phylogenetically conserved residues are identified that may be responsible for the vector-specific antagonist activity of domain III.
Rapid and Irreversible CD4+T-Cell Depletion Induced by the Highly Pathogenic Simian/Human Immunodeficiency Virus SHIVDH12RIs Systemic and Synchronous
Authors: Igarashi Tatsuhiko , Brown Charles R. , Byrum Russell A. , Nishimura Yoshiaki , Endo Yasuyuki , Plishka Ronald J. , Buckler Charles , Buckler-White Alicia , Miller Georgina , Hirsch Vanessa M. , Martin Malcolm A. 
Published: July 2002

ABSTRACTHighly pathogenic simian/human immunodeficiency virus chimeric viruses are known to induce a rapid, irreversible depletion of CD4+T lymphocytes in the peripheral blood of acutely infected macaque monkeys. To more fully assess the systemic effects of this primary virus infection, specimens were collected serially between days 3 and 21 postinfection from variety of lymphoid tissues (lymph nodes, thymus, and spleen) and gastrointestinal tract and examined by DNA and RNA PCR, in situ hybridization, and immunohistochemical assays. In addition, the lymphoid tissues were evaluated by fluorescence-activated cell sorting. Virus infection was initially detected by DNA PCR on day 3 postinfection in lymph node samples and peaked on day 10 in the T-lymphocyte-rich areas of this tissue. CD4+T-cell levels remained stable through day 10 in several lymphoid tissue specimens examined but fell precipitously between days 10 and 21. In situ terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) assays revealed the accumulation of apoptotic cells during the second week of infection in both lymph nodes and thymus, which colocalized, to a large extent, to sites of both virus replication and CD4+T-lymphocyte loss.
Hepatic DR5 Induces Apoptosis and Limits Adenovirus Gene Therapy Product Expression in the Liver
Authors: Zhang Huang-Ge , Xie Jinfu , Xu Liang , Yang Pingar , Xu Xin , Sun Sheher , Wang Yongming , Curiel David T. , Hsu Hui-Chen , Mountz John D. 
Published: July 2002

ABSTRACTA major limitation of adenovirus (Ad) gene therapy product expression in the liver is subsequent elimination of the hepatocytes expressing the gene therapy product. This elimination is caused by both necrosis and apoptosis related to the innate and cell-mediated immune response to the Ad. Apoptosis of hepatocytes can be induced by the innate immune response by signaling through death domain receptors on hepatocytes including the tumor necrosis factor alpha (TNF-α) receptor (TNFR), Fas, and death domain receptors DR4 and DR5. We have previously shown that blocking signaling through TNFR enhances and prolongs gene therapy product expression in the liver. In the present study, we constructed an Ad that produces a soluble DR5-Fc (AdsDR5), which is capable of neutralizing TNF-related apoptosis-inducing ligand (TRAIL). AdsDR5 prevents TRAIL-mediated apoptosis of CD3-activated T cells and decreases hepatocyte apoptosis after AdCMVLacZ administration and enhances the level and duration oflacZtransgene expression in the liver. In addition to blocking TRAIL and directly inhibiting apoptosis, AdsDR5 decreases production of gamma interferon (IFN-γ) and TNF-α and decreases NK cell activation, all of which limit Ad-mediated transgene expression in the liver. These results indicate that (i) AdsDR5 produces a DR5-Fc capable of neutralizing TRAIL, (ii) AdsDR5 can reduce activation of NK cells and reduce induction of IFN-γ and TNF-α after Ad administration, and (iii) administration of AdsDR5 can enhance Ad gene therapy in the liver.
Identification of NF-κB-Dependent Gene Networks in Respiratory Syncytial Virus-Infected Cells
Authors: Tian Bing , Zhang Yuhong , Luxon Bruce A. , Garofalo Roberto P. , Casola Antonella , Sinha Mala , Brasier Allan R. 
Published: July 2002

ABSTRACTRespiratory syncytial virus (RSV) is a mucosa-restricted virus that is a leading cause of epidemic respiratory tract infections in children. In epithelial cells, RSV replication activates nuclear translocation of the inducible transcription factor nuclear factor κB (NF-κB) through proteolysis of its cytoplasmic inhibitor, IκB. In spite of a putative role in mediating virus-inducible gene expression, the spectrum of NF-κB-dependent genes induced by RSV infection has not yet been determined. To address this, we developed a tightly regulated cell system expressing a nondegradable, epitope-tagged IκBα isoform (Flag-IκBα Mut) whose expression could be controlled by exogenous addition of nontoxic concentrations of doxycycline. Flag-IκBα Mut expression potently inhibited IκBα proteolysis, NF-κB binding, and NF-κB-dependent gene transcription in cells stimulated with the prototypical NF-κB-activating cytokine tumor necrosis factor alpha (TNF-α) and in response to RSV infection. High-density oligonucleotide microarrays were then used to profile constitutive and RSV-induced gene expression in the absence or presence of Flag-IκBα Mut. Comparison of these profiles revealed 380 genes whose expression was significantly changed by the dominant-negative NF-κB. Of these, 236 genes were constitutive (not RSV regulated), and surprisingly, only 144 genes were RSV regulated, representing numerically ∼10% of the total population of RSV-inducible genes at this time point. Hierarchical clustering of the 144 RSV- and Flag-IκBα Mut-regulated genes identified two discrete gene clusters. The first group had high constitutive expression, and its expression levels fell in response to RSV infection. In this group, constitutive mRNA expression was increased by Flag-IκBα Mut expression, and the RSV-induced decrease in expression was partly inhibited. In the second group, constitutive expression was very low (or undetectable) and, after RSV infection, expression levels strongly increased. In this group, NF-κB was required for RSV-inducible expression because Flag-IκBα Mut expression blocked their induction by RSV. This latter cluster includes chemokines, transcriptional regulators, intracellular proteins regulating translation and proteolysis, and secreted proteins (complement components and growth factor regulators). These data suggest that NF-κB action induces global cellular responses after viral infection.
Purification and Characterization of Oligomeric Envelope Glycoprotein from a Primary R5 Subtype B Human Immunodeficiency Virus
Authors: Srivastava Indresh K. , Stamatatos Leonidas , Legg Harold , Kan Elaine , Fong Anne , Coates Stephen R. , Leung Louisa , Wininger Mark , Donnelly John J. , Ulmer Jeffrey B. , Barnett Susan W. 
Published: July 2002

ABSTRACTHuman immunodeficiency virus (HIV) continues to be a major public health problem throughout the world, with high levels of mortality and morbidity associated with AIDS. Considerable efforts to develop an effective vaccine for HIV have been directed towards the generation of cellular, humoral, and mucosal immune responses. A major emphasis of our work has been toward the evaluation of oligomeric (o-gp140) forms of the HIV type 1 (HIV-1) envelope protein for their ability to induce neutralizing antibody responses. We have derived stable CHO cell lines expressing o-gp140 envelope protein from the primary non-syncytium-inducing (R5) subtype B strain HIV-1US4. We have developed an efficient purification strategy to purify oligomers to near homogeneity. Using a combination of three detectors measuring intrinsic viscosity, light scattering, and refractive index, we calculated the molecular mass of the oligomer to be 474 kDa, consistent with either a trimer or a tetramer. The hydrodynamic radius (Rh) of o-gp140 was determined to be 8.40 nm, compared with 5.07 nm for the monomer. The relatively smallerRhof the oligomer suggests that there are indeed differences between the foldings of o-gp140 and gp120. To assess the structural integrity of the purified trimers, we performed a detailed characterization of the glycosylation profile of o-gp140, its ability to bind soluble CD4, and also its ability to bind to a panel of monoclonal antibodies with known epitope specificities for the CD4 binding site, the CD4 inducible site, the V3 loop, and gp41. Immunogenicity studies with rabbits indicated that the purified o-gp140 protein was highly immunogenic and induced high-titer, high-avidity antibodies directed predominantly against conformational epitopes. These observations confirm the structural integrity of purified o-gp140 and its potential as a vaccine antigen.
Intra- and Intercellular Trafficking of the Foamy Virus Auxiliary Bet Protein
Authors: Lecellier Charles-Henri , Vermeulen Wim , Bachelerie Françoise , Giron Marie-Lou , Saïb Ali 
Published: July 2002

ABSTRACT
The Bet protein of foamy viruses (FVs) is an auxiliary protein encoded by the 3′ end of the viral genome. Although its function during the viral replication cycle is still unknown, Bet seems to play a key role in the establishment and/or maintenance of viral persistence, representing the predominant viral protein detected during chronic infection. To clarify the function of this viral protein, the subcellular distribution of Bet from the prototypic human foamy virus (HFV) was examined. We report here that this protein is distributed in both the cytoplasm and the nucleus of HFV-infected or Bet-transfected cells. The nuclear targeting results from the presence of a bipartite nuclear localization signal at the C-terminal region, sufficient to direct heterologous reporter proteins to the nucleus. Since HFV Bet spreads between cells, we show here that the secreted protein targets the nuclei of recipient cells. HFV Bet follows an unconventional route to exit the cell since its secretion is not affected by brefeldin A, a drug which disrupts the trafficking between the endoplasmic reticulum and the Golgi complex. Finally, these inter- and intracellular movements were also observed for the equine foamy virus Bet protein, strongly suggesting that these remarkable features are conserved among FVs.