bluuebunny/crossref_metadata_2025_split huggingface dataset:
Viral Protein VP4 Is a Target of Human Antibodies Enhancing Coxsackievirus B4- and B3-Induced Synthesis of Alpha Interferon
Authors: Chehadeh Wassim , Lobert Pierre-Emmanuel , Sauter Pierre , Goffard Anne , Lucas Bernadette , Weill Jacques , Vantyghem Marie-Christine , Alm Gunnar , Pigny Pascal , Hober Didier 
Published: October 2005

ABSTRACTCoxsackievirus B4 (CVB4)-induced production of alpha interferon (IFN-α) by peripheral blood mononuclear cells (PBMC) is enhanced in vitro by nonneutralizing anti-CVB4 antibodies from healthy subjects and, to a higher extent, from patients with insulin-dependent diabetes mellitus. In this study, we focused on identification of the viral target of these antibodies in CVB systems. High levels of IFN-α were obtained in supernatants of PBMC incubated with CVB4E2 or CVB3 and plasma from healthy subjects and, to a higher extent, from patients. The VP4 capsid proteins dissociated by heating at 56°C from CVB4E2 (VP4CVB4) and CVB3 (VP4CVB3) but not H antigen preincubated with plasma from healthy subjects or patients inhibited the plasma-dependent enhancement of CVB4E2- and CVB3-induced IFN-α synthesis. There was no cross-reaction between VP4CVB4and VP4CVB3in the inhibiting effect. IFN-α levels in culture supernatants showed dose-dependent correlation with anti-VP4 antibodies eluted from plasma specimens using VP4-coated plates. There were higher index values for anti-VP4 antibodies detected by enzyme-linked immunosorbent assay (ELISA) and higher proportions of positive detection in 40 patients than in 40 healthy subjects (80% versus 15% for anti-VP4CVB4). There was no relationship between the levels of anti-CVB neutralizing antibodies and the detection of anti-VP4 antibodies by ELISA. The CVB plasma-induced IFN-α levels obtained in PBMC cultures in the anti-VP4 antibody-positive groups were significantly higher than those obtained in the anti-VP4 antibody-negative groups regardless of the titers of anti-CVB neutralizing antibodies. These results show that VP4 is the target of antibodies involved in the plasma-dependent enhancement of CVB4E2- and CVB3-induced IFN-α synthesis by PBMC.
Inhibition of Polyprotein Processing and RNA Replication of Human Rhinovirus by Pyrrolidine Dithiocarbamate Involves Metal Ions
Authors: Krenn B. M. , Holzer B. , Gaudernak E. , Triendl A. , van Kuppeveld F. J. , Seipelt J. 
Published: October 2005

ABSTRACTPyrrolidine dithiocarbamate (PDTC) is an antiviral compound that was shown to inhibit the replication of human rhinoviruses (HRVs), poliovirus, and influenza virus. To elucidate the mechanism of PDTC, the effects on the individual steps of the infection cycle of HRV were investigated. PDTC did not interfere with receptor binding or internalization by receptor mediated endocytosis of HRV2 particles into HeLa cells. But we demonstrate that the processing of the viral polyprotein was prevented by PDTC treatment in HeLa cells infected with HRV2. Furthermore, PDTC inhibited the replication of the viral RNA, even when added four hours post infection. As PDTC is described as a metal ion binding agent, we investigated the effect of other metal chelators on the multiplication of HRV2. We show that EDTA,ο-phenanthroline, and bathocuproine disulfonic acid do not exhibit any antiviral properties. Surprisingly, these substances, coadministered with PDTC, abolished the antiviral effect of PDTC, suggesting that metal ions play a pivotal role in the inhibition of virus multiplication. These results suggest that PDTC inhibits the activity of the viral proteases in a metal ion dependent way.
Modulation of the Immune Response to the Severe Acute Respiratory Syndrome Spike Glycoprotein by Gene-Based and Inactivated Virus Immunization
Authors: Kong Wing-pui , Xu Ling , Stadler Konrad , Ulmer Jeffrey B. , Abrignani Sergio , Rappuoli Rino , Nabel Gary J. 
Published: October 2005

ABSTRACTAlthough the initial isolates of the severe acute respiratory syndrome (SARS) coronavirus (CoV) are sensitive to neutralization by antibodies through their spike (S) glycoprotein, variants of S have since been identified that are resistant to such inhibition. Optimal vaccine strategies would therefore make use of additional determinants of immune recognition, either through cellular or expanded, cross-reactive humoral immunity. Here, the cellular and humoral immune responses elicited by different combinations of gene-based and inactivated viral particles with various adjuvants have been assessed. The T-cell response was altered by different prime-boost immunizations, with the optimal CD8 immunity induced by DNA priming and replication-defective adenoviral vector boosting. The humoral immune response was enhanced most effectively through the use of inactivated virus with adjuvants, either MF59 or alum, and was associated with stimulation of the CD4 but not the CD8 response. The use of inactivated SARS virus with MF59 enhanced the CD4 and antibody response even after gene-based vaccination. Because both cellular and humoral immune responses are generated by gene-based vaccination and inactivated viral boosting, this strategy may prove useful in the generation of SARS-CoV vaccines.
Robust Production of Infectious Hepatitis C Virus (HCV) from Stably HCV cDNA-Transfected Human Hepatoma Cells
Authors: Cai Zhaohui , Zhang Chen , Chang Kyung-Soo , Jiang Jieyun , Ahn Byung-Chul , Wakita Takaji , Liang T. Jake , Luo Guangxiang 
Published: October 2005

ABSTRACT

Hepatitis C virus (HCV) chronically infects approximately 170 million people worldwide, with an increased risk of developing cirrhosis and hepatocellular carcinoma. The study of HCV replication and pathogenesis has been hampered by the lack of an efficient stable cell culture system and small-animal models of HCV infection and propagation. In an effort to develop a robust HCV infection system, we constructed stable human hepatoma cell lines that contain a chromosomally integrated genotype 2a HCV cDNA and constitutively produce infectious virus. Transcriptional expression of the full-length HCV RNA genome is under the control of a cellular Pol II polymerase promoter at the 5′ end and a hepatitis delta virus ribozyme at the 3′ end. The resulting HCV RNA was expressed and replicated efficiently, as shown by the presence of high levels of HCV proteins as well as both positive- and negative-strand RNAs in the stable Huh7 cell lines. Stable cell lines robustly produce HCV virions with up to 10
8
copies of HCV viral RNA per milliliter (ml) of the culture medium. Subsequent infection of naïve Huh7.5 cells with HCV released from the stable cell lines resulted in high levels of HCV proteins and RNAs. Additionally, HCV infection was inhibited by monoclonal antibodies specific to CD81 and the HCV envelope glycoproteins E1 and E2, and HCV replication was suppressed by alpha interferon. Collectively, these results demonstrate the establishment of a stable HCV culture system that robustly produces infectious virus, which will allow the study of each aspect of the entire HCV life cycle.
Identification of Interferon-Stimulated Gene 15 as an Antiviral Molecule during Sindbis Virus Infection In Vivo
Authors: Lenschow Deborah J. , Giannakopoulos Nadia V. , Gunn Lacey J. , Johnston Christine , O'Guin Andy K. , Schmidt Robert E. , Levine Beth , Virgin Herbert W. 
Published: October 2005

ABSTRACTThe innate immune response, and in particular the alpha/beta interferon (IFN-α/β) system, plays a critical role in the control of viral infections. Interferons α and β exert their antiviral effects through the induction of hundreds of interferon-induced (or -stimulated) genes (ISGs). While several of these ISGs have characterized antiviral functions, their actions alone do not explain all of the effects mediated by IFN-α/β. To identify additional IFN-induced antiviral molecules, we utilized a recombinant chimeric Sindbis virus to express selected ISGs in IFN-α/β receptor (IFN-α/βR)−/−mice and looked for attenuation of Sindbis virus infection. Using this approach, we identified a ubiquitin homolog, interferon-stimulated gene 15 (ISG15), as having antiviral activity. ISG15 expression protected against Sindbis virus-induced lethality and decreased Sindbis virus replication in multiple organs without inhibiting the spread of virus throughout the host. We establish that, much like ubiquitin, ISG15 requires its C-terminal LRLRGG motif to form intracellular conjugates. Finally, we demonstrate that ISG15's LRLRGG motif is also required for its antiviral activity. We conclude that ISG15 can be directly antiviral.
Epstein-Barr Virus Lytic Infection Contributes to Lymphoproliferative Disease in a SCID Mouse Model
Authors: Hong Gregory K. , Gulley Margaret L. , Feng Wen-Hai , Delecluse Henri-Jacques , Holley-Guthrie Elizabeth , Kenney Shannon C. 
Published: October 2005

ABSTRACTMost Epstein-Barr virus (EBV)-positive tumor cells contain one of the latent forms of viral infection. The role of lytic viral gene expression in EBV-associated malignancies is unknown. Here we show that EBV mutants that cannot undergo lytic viral replication are defective in promoting EBV-mediated lymphoproliferative disease (LPD). Early-passage lymphoblastoid cell lines (LCLs) derived from EBV mutants with a deletion of either viral immediate-early gene grew similarly to wild-type (WT) virus LCLs in vitro but were deficient in producing LPD when inoculated into SCID mice. Restoration of lytic EBV gene expression enhanced growth in SCID mice. Acyclovir, which prevents lytic viral replication but not expression of early lytic viral genes, did not inhibit the growth of WT LCLs in SCID mice. Early-passage LCLs derived from the lytic-defective viruses had substantially decreased expression of the cytokine interleukin-6 (IL-6), and restoration of lytic gene expression reversed this defect. Expression of cellular IL-10 and viral IL-10 was also diminished in lytic-defective LCLs. These results suggest that lytic EBV gene expression contributes to EBV-associated lymphoproliferative disease, potentially through induction of paracrine B-cell growth factors.
The Vaccinia Virus F1L Protein Interacts with the Proapoptotic Protein Bak and Inhibits Bak Activation
Authors: Wasilenko Shawn T. , Banadyga Logan , Bond David , Barry Michele 
Published: October 2005

ABSTRACT

Many viruses have evolved strategies to counteract cellular immune responses, including apoptosis. Vaccinia virus, a member of the poxvirus family, encodes an antiapoptotic protein, F1L. F1L localizes to mitochondria and inhibits apoptosis by preventing the release of cytochrome
c
by an undetermined mechanism (S. T. Wasilenko, T. L. Stewart, A. F. Meyers, and M. Barry, Proc. Natl. Acad. Sci. USA
100:
14345-14350, 2003; T. L. Stewart, S. T. Wasilenko, and M. Barry, J. Virol.
79:
1084-1098, 2005). Here, we show that in the absence of an apoptotic stimulus, F1L associates with Bak, a proapoptotic member of the Bcl-2 family that plays a pivotal role in the release of cytochrome
c
. Cells infected with vaccinia virus were resistant to Bak oligomerization and the initial N-terminal exposure of Bak following the induction of apoptosis with staurosporine. A mutant vaccinia virus missing F1L was no longer able to inhibit apoptosis or Bak activation. In addition, the expression of F1L was essential to inhibit tBid-induced cytochrome
c
release in both wild-type murine embryonic fibroblasts (MEFs) and Bax-deficient MEFs, indicating that F1L could inhibit apoptosis in the presence and absence of Bax. tBid-induced Bak oligomerization and N-terminal exposure of Bak in Bax-deficient MEFs were inhibited during virus infection, as assessed by cross-linking and limited trypsin proteolysis. Infection with the F1L deletion virus no longer provided protection from tBid-induced Bak activation and apoptosis. Additionally, infection of Jurkat cells with the F1L deletion virus resulted in cellular apoptosis, as measured by loss of the inner mitochondrial membrane potential, caspase 3 activation, and cytochrome
c
release, indicating that the presence of F1L was pivotal for inhibiting vaccinia virus-induced apoptosis. Our data indicate that F1L expression during infection inhibits apoptosis and interferes with the activation of Bak.
Immunodeficiency in the Absence of High Viral Load in Pig-Tailed Macaques Infected with Simian Immunodeficiency Virus SIVsun or SIVlhoest
Authors: Beer Brigitte E. , Brown Charles R. , Whitted Sonya , Goldstein Simoy , Goeken Robert , Plishka Ronald , Buckler-White Alicia , Hirsch Vanessa M. 
Published: October 2005

ABSTRACT

Simian immunodeficiency virus (SIV) is known to result in an asymptomatic infection of its natural African monkey host. However, some SIV strains are capable of inducing AIDS-like symptoms and death upon experimental infection of Asian macaques. To further investigate the virulence of natural SIV isolates from African monkeys, pig-tailed (PT) macaques were inoculated intravenously with either of two recently discovered novel lentiviruses, SIVlhoest and SIVsun. Both viruses were apparently apathogenic in their natural hosts but caused immunodeficiency in PT macaques. Infection was characterized by a progressive loss of CD4
+
lymphocytes in the peripheral blood and lymph nodes, generalized lymphoid depletion, a wasting syndrome, and opportunistic infections, such as
Mycobacterium avium
or
Pneumocystis carinii
infections. However, unlike SIVsm/mac infection of macaques, SIVlhoest and SIVsun infections in PT macaques were not accompanied by high viral loads during the chronic disease stage. In addition, no significant correlation between the viral load at set point (12 weeks postinfection) and survival could be found. Five out of eight SIVlhoest-infected and three out of four SIVsun-infected macaques succumbed to AIDS during the first 5 years of infection. Thus, the survival of SIVsun- and SIVlhoest-infected animals was significantly longer than that of SIVagm- or SIVsm-infected macaques. All PT macaques maintained strong SIV antibody responses despite progression to SIV-induced AIDS. The development of immunodeficiency in the face of low viremia suggests that SIVlhoest and SIVsun infections of macaques may model unique aspects of the pathogenesis of human immunodeficiency virus infection in humans.
Phosphorylation of the Herpes Simplex Virus Tegument Protein VP22 Has No Effect on Incorporation of VP22 into the Virus but Is Involved in Optimal Expression and Virion Packaging of ICP0
Authors: Potel Corinne , Elliott Gillian 
Published: October 2005

ABSTRACT
Herpes simplex virus VP22 is a major tegument protein of unknown function. Very recently, we reported that the predominant effect of deleting the VP22 gene was on the expression, localization, and virion incorporation of ICP0. In addition, the Δ22 virus replicated poorly in epithelial MDBK cells. We have also previously shown that VP22 interacts with the tegument protein VP16 and the cellular microtubule network. While the majority of VP22 in infected cells is highly phosphorylated, the nonphosphorylated form of VP22 is the predominant species in the virion, suggesting a differential requirement for phosphorylation through virus replication. Hence, to study the significance of VP22 phosphorylation, we have now constructed two recombinant viruses expressing green fluorescent protein-VP22 (G22) in which the previously identified serine phosphorylation sites have been mutated either to alanine to abolish the phosphorylation status of VP22 (G22P−) or to glutamic acid to mimic permanent phosphorylation (G22P+). Localization studies indicated that the G22P− protein associated tightly with microtubules in some infected cells, suggesting that VP22 phosphorylation may control its interaction with the microtubule network. By contrast, VP22 phosphorylation had no effect on its ability to interact with VP16 and, importantly, had no effect on the relative packaging of VP22. Intriguingly, virion packaging of ICP0 was reduced in the G22P+ virus while ICP0 expression was reduced in the G22P− virus, suggesting that these two ICP0 defects, previously observed in the Δ22 virus, were attributable to different forms of VP22. Furthermore, the Δ22 virus replication defect in MDBK cells correlated with the expression of constitutively charged VP22 in the G22P+ virus. Taken together, these results suggest an important role for VP22 phosphorylation in its relationship with ICP0.
Crystal Structure of Enteric Adenovirus Serotype 41 Short Fiber Head
Authors: Seiradake Elena , Cusack Stephen 
Published: October 2005

ABSTRACT
Human enteric adenoviruses of species F contain two fibers in the same virion, a long fiber which binds to coxsackievirus and adenovirus receptor (CAR) and a short fiber of unknown function. We have determined the high-resolution crystal structure of the short fiber head of human adenovirus serotype 41 (Ad41). The short fiber head has the characteristic fold of other known fiber heads but has three unusual features. First, it has much shorter loops between the beta-strands. Second, one of the usually well-ordered beta-strands on the distal face of the fiber head is highly disordered and this same region is sensitive to digestion with pepsin, an enzyme occurring naturally in the intestinal tract, the physiological environment of Ad41. Third, the AB loop has a deletion giving it a distinct conformation incompatible with CAR binding.
Gene and Genome Duplication in
Acanthamoeba polyphaga Mimivirus
Authors: Suhre Karsten 
Published: October 2005

ABSTRACT

Gene duplication is key to molecular evolution in all three domains of life and may be the first step in the emergence of new gene function. It is a well-recognized feature in large DNA viruses but has not been studied extensively in the largest known virus to date, the recently discovered
Acanthamoeba polyphaga Mimivirus
. Here, I present a systematic analysis of gene and genome duplication events in the mimivirus genome. I found that one-third of the mimivirus genes are related to at least one other gene in the mimivirus genome, either through a large segmental genome duplication event that occurred in the more remote past or through more recent gene duplication events, which often occur in tandem. This shows that gene and genome duplication played a major role in shaping the mimivirus genome. Using multiple alignments, together with remote-homology detection methods based on Hidden Markov Model comparison, I assign putative functions to some of the paralogous gene families. I suggest that a large part of the duplicated mimivirus gene families are likely to interfere with important host cell processes, such as transcription control, protein degradation, and cell regulatory processes. My findings support the view that large DNA viruses are complex evolving organisms, possibly deeply rooted within the tree of life, and oppose the paradigm that viral evolution is dominated by lateral gene acquisition, at least in regard to large DNA viruses.
Epstein-Barr Virus mRNA Export Factor EB2 Is Essential for Intranuclear Capsid Assembly and Production of gp350
Authors: Batisse Julien , Manet Evelyne , Middeldorp Jaap , Sergeant Alain , Gruffat Henri 
Published: October 2005

ABSTRACT

Most human herpesviruses, including Epstein-Barr virus (EBV), express a protein which functions primarily as an mRNA export factor. Previously, we deleted the gene for the Epstein-Barr virus mRNA export factor EB2 from the EBV genome and then introduced the mutated genome into 293 cells. Using a transcomplementation assay in which ectopic expression of the transcription factor EB1/ZEBRA was sufficient to induce the EBV productive cycle, we showed that Ori-Lyt-dependent replication of the EBV DNA occurs in the absence of EB2, indicating that EB2 is not essential for the expression and export of early mRNAs. However, in the absence of EB2, no infectious viral particles are produced (H. Gruffat, J. Batisse, D. Pich, B. Neuhierl, E. Manet, W. Hammerschmidt, and A. Sergeant, J. Virol.
76:
9635-9644, 2002). In this report, we now show that EB2 is essential for the nuclear export of most, but not all, late mRNAs produced from intronless genes that translate into proteins involved in intranuclear capsid assembly and maturation. As a consequence, we show that EB2 is essential for the proper assembly of intranuclear capsids. Interestingly, the late BLLF1 gene contains an intron, and both unspliced and spliced mRNAs must be exported to the cytoplasm to be translated into gp350 and gp220, respectively (M. Hummel, D. A. Thorley-Lawson, and E. Kieff, J. Virol.
49:
413-417, 1984). Our results also demonstrate that although BLLF1 spliced mRNAs are exported to the cytoplasm independently of EB2, EB2 is essential for the nuclear export of unspliced BLLF1 mRNA. In the same assay, herpes simplex virus 1 ICP27 completely inhibited the nuclear export of BLLF1 spliced mRNAs whereas unspliced BLLF1 mRNAs were exported, confirming that in a physiological assay, ICP27 inhibits splicing.
Association of Human Immunodeficiency Virus Type 1 Gag with Membrane Does Not Require Highly Basic Sequences in the Nucleocapsid: Use of a Novel Gag Multimerization Assay
Authors: Ono Akira , Waheed Abdul A. , Joshi Anjali , Freed Eric O. 
Published: October 2005

ABSTRACT
Human immunodeficiency virus type 1 (HIV-1) particle production, a process driven by the Gag polyprotein precursor, occurs on the plasma membrane in most cell types. The plasma membrane contains cholesterol-enriched microdomains termed lipid rafts, which can be isolated as detergent-resistant membrane (DRM). Previously, we and others demonstrated that HIV-1 Gag is associated with DRM and that disruption of Gag-raft interactions impairs HIV-1 particle production. However, the determinants of Gag-raft association remain undefined. In this study, we developed a novel epitope-based Gag multimerization assay to examine whether Gag assembly is essential for its association with lipid rafts. We observed that membrane-associated, full-length Gag is poorly detected by immunoprecipitation relative to non-membrane-bound Gag. This poor detection is due to assembly-driven masking of Gag epitopes, as denaturation greatly improves immunoprecipitation. Gag mutants lacking the Gag-Gag interaction domain located in the N terminus of the nucleocapsid (NC) were efficiently immunoprecipitated without denaturation, indicating that the epitope masking is caused by higher-order Gag multimerization. We used this assay to examine the relationship between Gag assembly and Gag binding to total cellular membrane and DRM. Importantly, a multimerization-defective NC mutant displayed wild-type levels of membrane binding and DRM association, indicating that NC-mediated Gag multimerization is dispensable for association of Gag with membrane or DRM. We also demonstrate that different properties of sucrose and iodixanol membrane flotation gradients may explain some discrepancies regarding Gag-raft interactions. This report offers new insights into the association of HIV-1 Gag with membrane and with lipid rafts.