bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genomes of the Parapoxviruses Orf Virus and Bovine Papular Stomatitis Virus
Authors: Delhon G. , Tulman E. R. , Afonso C. L. , Lu Z. , de la Concha-Bermejillo A. , Lehmkuhl H. D. , Piccone M. E. , Kutish G. F. , Rock D. L. 
Published: December 2003

ABSTRACT

Bovine papular stomatitis virus
(BPSV) and
orf virus
(ORFV), members of the genus
Parapoxvirus
of the
Poxviridae
, are etiologic agents of worldwide diseases affecting cattle and small ruminants, respectively. Here we report the genomic sequences and comparative analysis of BPSV strain BV-AR02 and ORFV strains OV-SA00, isolated from a goat, and OV-IA82, isolated from a sheep. Parapoxvirus (PPV) BV-AR02, OV-SA00, and OV-IA82 genomes range in size from 134 to 139 kbp, with an average nucleotide composition of 64% G+C. BPSV and ORFV genomes contain 131 and 130 putative genes, respectively, and share colinearity over 127 genes, 88 of which are conserved in all characterized chordopoxviruses. BPSV and ORFV contain 15 and 16 open reading frames (ORFs), respectively, which lack similarity to other poxvirus or cellular proteins. All genes with putative roles in pathogenesis, including a vascular endothelial growth factor (VEGF)-like gene, are present in both viruses; however, BPSV contains two extra ankyrin repeat genes absent in ORFV. Interspecies sequence variability is observed in all functional classes of genes but is highest in putative virulence/host range genes, including genes unique to PPV. At the amino acid level, OV-SA00 is 94% identical to OV-IA82 and 71% identical to BV-AR02. Notably, ORFV 006/132, 103, 109, 110, and 116 genes (VEGF, homologues of vaccinia virus A26L, A33R, and A34R, and a novel PPV ORF) show an unusual degree of intraspecies variability. These genomic differences are consistent with the classification of BPSV and ORFV as two PPV species. Compared to other mammalian chordopoxviruses, PPV shares unique genomic features with molluscum contagiosum virus, including a G+C-rich nucleotide composition, three orthologous genes, and a paucity of nucleotide metabolism genes. Together, these data provide a comparative view of PPV genomics.
Inefficient Signalase Cleavage Promotes Efficient Nucleocapsid Incorporation into Budding Flavivirus Membranes
Authors: Lobigs Mario , Lee Eva 
Published: December 2003

ABSTRACT
The mechanism for efficient nucleocapsid (NC) uptake into flavivirus particles which form by budding through the membranes of the endoplasmic reticulum (ER) was investigated by using Murray Valley encephalitis virus as a model. Budding of flavivirus membranes is driven by the viral transmembrane proteins prM and E independently of NC interaction. We show that control of signalase cleavage of the multimembrane-spanning flavivirus polyprotein by the catalytic function of the viral protease is critical for efficient virus morphogenesis. In wild-type virus, signalase cleavage of prM remains inefficient until cleavage of capsid at the cytosolic side of the signal sequence separating the two proteins has occurred. This obligatory sequence of cleavages was uncoupled in a mutant virus with the consequence of greatly reduced incorporation of NC into budding membranes and augmented release of NC-free virus-like particles. Efficient signalase cleavage of prM in the mutant virus resulted in partial inhibition of cleavage of capsid by the viral NS2B-3 protease. Our results support a model for flavivirus morphogenesis involving temporal and spatial coordination of NC assembly and envelopment by regulated cleavages of an ER membrane-spanning capsid-prM intermediate.
Control of Heterologous Hepatitis C Virus Infection in Chimpanzees Is Associated with the Quality of Vaccine-Induced Peripheral T-Helper Immune Response
Authors: Rollier C. , Depla E. , Drexhage J. A. R. , Verschoor E. J. , Verstrepen B. E. , Fatmi A. , Brinster C. , Fournillier A. , Whelan J. A. , Whelan M. , Jacobs D. , Maertens G. , Inchauspé G. , Heeney J. L. 
Published: December 2003

ABSTRACTProphylactic hepatitis C virus (HCV) vaccine trials with human volunteers are pending. There is an important need for immunological end points which correlate with vaccine efficacy and which do not involve invasive procedures, such as liver biopsies. By using a multicomponent DNA priming-protein boosting vaccine strategy, naïve chimpanzees were immunized against HCV structural proteins (core, E1, and E2) as well as a nonstructural (NS3) protein. Following immunization, exposure to the heterologous HCV 1b J4 subtype resulted in a peak of plasma viremia which was lower in both immunized animals. Compared to the naïve infection control and nine additional historical controls which became chronic, vaccinee 2 (Vac2) rapidly resolved the infection, while the other (Vac1) clearly controlled HCV infection. Immunization induced antibodies, peptide-specific gamma interferon (IFN-γ), protein-specific lymphoproliferative responses, IFN-γ, interleukin-2 (IL-2), and IL-4 T-helper responses in both vaccinees. However, the specificities were markedly different: Vac2 developed responses which were lower in magnitude than those of Vac1 but which were biased towards Th1-type cytokine responses for E1 and NS3. This proof-of-principle study in chimpanzees revealed that immunization with a combination of nonstructural and structural antigens elicited T-cell responses associated with an alteration of the course of infection. Our findings provide data to support the concept that the quality of the response to conserved epitopes and the specific nature of the peripheral T-helper immune response are likely pivotal factors influencing the control and clearance of HCV infection.
Evasion of Cellular Antiviral Responses by Human Cytomegalovirus
TRS1
and
IRS1
Authors: Child Stephanie J. , Hakki Morgan , De Niro Katherine L. , Geballe Adam P. 
Published: December 2003

ABSTRACT

During infection with human cytomegalovirus (HCMV), cellular protein synthesis continues even as viral proteins are being synthesized in abundance. Thus, HCMV may have a mechanism for counteracting host cell antiviral pathways that act by shutting off translation. Consistent with this view, HCMV infection of human fibroblasts rescues the replication of a vaccinia virus mutant lacking the double-stranded RNA-binding protein gene E3L (VVΔE3L). HCMV also prevents the phosphorylation of the eukaryotic translation initiation factor eIF-2α, the activation of RNase L, and the shutoff of viral and cellular protein synthesis that otherwise result from VVΔE3L infection. To identify the HCMV gene(s) responsible for these effects, we prepared a library of VVΔE3L recombinants containing HCMV genomic fragments. By infecting nonpermissive cells with this library and screening for VV gene expression and replication, we isolated a virus containing a 2.8-kb HCMV fragment that rescues replication of VVΔE3L. The fragment comprises the 3′ end of the J1S open reading frame through the entire
TRS1
gene. Analyses of additional VVΔE3L recombinants revealed that the protein encoded by
TRS1
, pTRS1, as well as the closely related
IRS1
gene, rescues VVΔE3L replication and prevent the shutoff of protein synthesis, the phosphorylation of eIF-2α, and activation of RNase L. These results demonstrate that
TRS1
and
IRS1
are able to counteract critical host cell antiviral response pathways.
Subsets of Memory Cytotoxic T Lymphocytes Elicited by Vaccination Influence the Efficiency of Secondary Expansion In Vivo
Authors: Seaman Michael S. , Peyerl Fred W. , Jackson Shawn S. , Lifton Michelle A. , Gorgone Darci A. , Schmitz Jörn E. , Letvin Norman L. 
Published: December 2003

ABSTRACTVaccine-elicited cytotoxic T lymphocytes (CTL) should be long-lived memory cells that can rapidly expand in number following re-exposure to antigen. The present studies were initiated to analyze the ability of plasmid interleukin-12 (IL-12) to augment CTL responses in mice when delivered during the peak phase of an immune response elicited by a plasmid human immunodeficiency virus type 1 gp120 DNA vaccine. Delivery of plasmid IL-12 on day 10 postimmunization resulted in a robust expansion of gp120-specific CD8+T cells, as measured by tetramer, gamma interferon ELISPOT, and functional-killing assays. Interestingly, this delayed administration of plasmid IL-12 had no significant effect on antigen-specific CD4+-T-cell and antibody responses. Phenotypic analyses suggested that administration of plasmid IL-12 near the time of the peak CTL response activated and expanded antigen-specific effector cells, preventing their loss through apoptosis. However, this IL-12-augmented population of gp120-specific CD8+T cells did not efficiently expand following gp120 boost immunization, suggesting that these effector cells would be of little utility in expanding to contain a viral infection. Analyses of the phenotypic profile and anatomic distribution of the plasmid IL-12-augmented CTL population indicated that these lymphocytes were primarily effector memory rather than central memory T cells. These observations suggest that CTL-based vaccines should elicit central memory rather than effector memory T cells and illustrate the importance of monitoring the phenotype and functionality of vaccine-induced, antigen-specific CTL.
N-Terminal Domain of the Murine Coronavirus Receptor CEACAM1 Is Responsible for Fusogenic Activation and Conformational Changes of the Spike Protein
Authors: Miura Hideka S. , Nakagaki Keiko , Taguchi Fumihiro 
Published: December 2003

ABSTRACT
The mouse hepatitis virus (MHV) receptor (MHVR), CEACAM1, has two different functions for MHV entry into cells: binding to MHV spike protein (S protein) and activation of the S protein to execute virus-cell membrane fusion, the latter of which is accompanied by conformational changes of the S protein. The MHVR comprising the N-terminal and fourth domains [R1(1,4)] displays these two activities, and the N domain is thought to be critical for binding to MHV. In this study, we have addressed whether or not the N domain alone is sufficient for these activities. We examined three types of soluble form MHVR (soMHVR), one consisting of the N domain alone [soR1(1)], one with the N and second domains [soR1(1,2)], and one [soR1(1,4)] expressed by recombinant baculoviruses. We assessed the abilities of these three types of soMHVR to bind to MHV, activate fusogenicity, and induce conformational changes of the S protein. All three types of soMHVR similarly bound to MHV, as examined by a solid-phase binding assay and neutralized MHV infectivity. They also activated S protein fusogenicity and induced its conformational changes with similar levels of efficiency. However, R1(1) expressed on the BHK cell surface failed to serve as a receptor in spite of a sufficient level of expression. The inability of expressed R1(1) to work as a receptor was due to the inaccessibility of virions to R1(1); however, these were accessible using the MHVR-specific monoclonal antibody CC1. These results collectively indicated that the N domain retains all biological activities necessary for receptor function.
Herpes Simplex Virus Type 1 Immediate-Early Gene Expression Is Required for the Induction of Apoptosis in Human Epithelial HEp-2 Cells
Authors: Sanfilippo Christine M. , Chirimuuta Fungai N. W. , Blaho John A. 
Published: December 2003

ABSTRACT

Wild-type herpes simplex virus type 1 (HSV-1) induces apoptosis in human epithelial HEp-2 cells, but infected cell proteins produced later in infection block the process from killing the cells. Thus, HSV-1 infection in the presence of the translational inhibitor cycloheximide (CHX) results in apoptosis. Our specific goal was to gain insight as to the viral feature(s) responsible for triggering apoptosis during HSV-1 infection. We now report the following. (i) No viral protein synthesis or death factor processing was detected after infection with HSV-1(HFEM
ts
B7) at 39.5°C; this mutant virus does not inject its virion DNA into the nucleus at this nonpermissive temperature. (ii) No death factor processing or apoptotic morphological changes were detected following infection with UV-irradiated, replication-defective viruses possessing transcriptionally active incoming VP16. (iii) Addition of the transcriptional inhibitor actinomycin D prevented death factor processing upon infection with the apoptotic, ICP27-deletion virus HSV-1(vBSΔ27). (iv) Apoptotic morphologies and death factor processing were not observed following infection with HSV-1(
d
109), a green fluorescent protein-expressing recombinant virus possessing deletions of all five immediate-early (IE) (or α) genes. (v) Finally, complete death factor processing was observed upon infection with the VP16 transactivation domain-mutant HSV-1(V422) in the presence of CHX. Based on these findings, we conclude that (vi) the expression of HSV-1 α/IE genes is required for the viral induction of apoptosis and (vii) the transactivation activity of VP16 is not necessary for this induction.
ICP27 Selectively Regulates the Cytoplasmic Localization of a Subset of Viral Transcripts in Herpes Simplex Virus Type 1-Infected Cells
Authors: Pearson Angela , Knipe David M. , Coen Donald M. 
Published: December 2003

ABSTRACT

Evidence suggests that the herpes simplex virus regulatory protein ICP27 mediates the nuclear export of viral transcripts; however, the extent of this activity during infection is unclear. ICP27 is required for efficient expression of the long, leaky-late
UL24
transcripts, but not for that of the short, early
UL24
transcripts. We found that infection by an
ICP27
-null mutant resulted in undetectable UL24 protein expression, which represented at least a 70-fold decrease relative to that of wild-type virus. Because lack of ICP27 had a greater effect on levels of UL24 protein than on transcripts, we examined its effect on subcellular localization of
UL24
transcripts. In wild-type-infected cells, both short and long
UL24
transcripts fractionated predominantly with the cytoplasm. However, in the absence of ICP27, greater than 50% of long
UL24
transcripts were nuclear, while the percentage of short
UL24
transcripts that were cytoplasmic was not reduced. These results also imply that the short
UL24
transcripts are translated poorly. The effect of ICP27 on cytoplasmic localization of the long
UL24
transcripts did not extend to other transcripts with which it shared a common 3′ end or to other transcripts tested, including
gC
and
UL42
, whose overall expression is highly dependent on ICP27. Thus, the dual effects of ICP27 on mRNA accumulation and cytoplasmic localization are not always linked. These results identify viral transcripts that are dependent on ICP27 for efficient cytoplasmic localization during infection, but they also indicate the existence of ICP27-independent nuclear export pathways that are accessible to many viral transcripts during infection.
Structural Differences among Hemagglutinins of Influenza A Virus Subtypes Are Reflected in Their Antigenic Architecture: Analysis of H9 Escape Mutants
Authors: Kaverin Nikolai V. , Rudneva Irina A. , Ilyushina Natalia A. , Lipatov Aleksandr S. , Krauss Scott , Webster Robert G. 
Published: December 2003

ABSTRACT
We used a panel of monoclonal antibodies to H9 hemagglutinin to select 18 escape mutants of mouse-adapted influenza A/Swine/Hong Kong/9/98 (H9N2) virus. Cross-reactions of the mutants with the antibodies and the sequencing of hemagglutinin genes revealed two minimally overlapping epitopes. We mapped the amino acid changes to two areas of the recently reported three-dimensional structure of A/Swine/Hong Kong/9/98 hemagglutinin. The grouping of the antigenically relevant amino acid positions in H9 hemagglutinin differs from the pattern observed in H3 and H5 hemagglutinins. Several positions in site B of H3 hemagglutinin are distributed in two sites of H9 hemagglutinin. Unlike any subtype analyzed so far, H9 hemagglutinin does not contain an antigenic site corresponding to site A in H3 hemagglutinin. Positions 145 and 193 (H3 numbering), which in H3 hemagglutinin belong to sites A and B, respectively, are within one site in H9 hemagglutinin. This finding is consistent with the peculiarity of the three-dimensional structure of the H9 molecule, that is, the absence from H9 hemagglutinin of the lateral loop that forms site A in H3 and the equivalent site in H5 hemagglutinins. The escape mutants analyzed displayed phenotypic variations, including decreased virulence for mice and changes in affinity for sialyl substrates. Our results demonstrate a correlation between intersubtype differences in three-dimensional structure and variations among subtypes in the distribution of antigenic areas. Our findings also suggest that covariation and pleiotropic effects of antibody-selected mutations may be important in the evolution of H9 influenza virus, a possible causative agent of a future pandemic.
A JC Virus-Induced Signal Is Required for Infection of Glial Cells by a Clathrin- and eps15-Dependent Pathway
Authors: Querbes W. , Benmerah A. , Tosoni D. , Di Fiore P. P. , Atwood Walter J. 
Published: December 2003

ABSTRACT
Infectious entry of JC virus (JCV) into human glial cells occurs by receptor-mediated clathrin-dependent endocytosis. In this report we demonstrate that the tyrosine kinase inhibitor genistein blocks virus entry and inhibits infection. Transient expression of dominant-negative eps15 mutants, including a phosphorylation-defective mutant, inhibited both virus entry and infection. We also show that the JCV-induced signal activates the mitogen-activated protein kinases ERK1 and ERK2. These data demonstrate that JC virus binding to human glial cells induces an intracellular signal that is critical for entry and infection by a ligand-inducible clathrin-dependent mechanism.
Immune Failure in the Absence of Profound CD4+T-Lymphocyte Depletion in Simian Immunodeficiency Virus-Infected Rapid Progressor Macaques
Authors: Hirsch Vanessa M. , Santra Sampa , Goldstein Simoy , Plishka Ronald , Buckler-White Alicia , Seth Aruna , Ourmanov Ilnour , Brown Charles R. , Engle Ronald , Montefiori David , Glowczwskie Jennifer , Kunstman Kevin , Wolinsky Steven , Letvin Norman L. 
Published: December 2003

ABSTRACTA fraction of simian immunodeficiency virus (SIV)-infected macaques develop rapidly progressive disease in the apparent absence of detectable SIV-specific antibody responses. To characterize the immunopathogenesis of this syndrome, we studied viral load, CD4+T-lymphocyte numbers as well as cellular and humoral immune responses to SIV and other exogenous antigens in four SIVsm-infected rhesus macaques that progressed to AIDS 9 to 16 weeks postinoculation. Each of these animals exhibited high levels of viremia but showed relatively preserved CD4 T lymphocytes in blood and lymphoid tissues at the time of death. Transient SIV-specific antibody responses and cytotoxic T-lymphocyte responses were observed at 2 to 4 weeks postinoculation. Two of the macaques that were immunized sequentially with tetanus toxoid and hepatitis A virus failed to develop antibody to either antigen. These studies show that the SIV-infected rapid progressor macaques initially mounted an appropriate but transient cellular and humoral immune response. The subsequent immune defect in these animals appeared to be global, affecting both cellular and humoral immunity to SIV as well as immune responses against unrelated antigens. The lack of CD4 depletion and loss of humoral and cellular immune responses suggest that their immune defect may be due to an early loss in T helper function.
Phosphorylation of Human Cytomegalovirus Glycoprotein B (gB) at the Acidic Cluster Casein Kinase 2 Site (Ser
900
) Is Required for Localization of gB to the
trans-
Golgi Network and Efficient Virus Replication
Authors: Jarvis Michael A. , Jones Thomas R. , Drummond Derek D. , Smith Patsy P. , Britt William J. , Nelson Jay A. , Baldick Carl J. 
Published: December 2003

ABSTRACT

Human cytomegalovirus (HCMV) glycoprotein B (gB), encoded by the UL55 open reading frame, is an essential envelope glycoprotein involved in cell attachment and entry. Previously, we identified residue serine 900 (Ser
900
) as a unique site of reversible casein kinase 2 phosphorylation in the cytoplasmic domain of HCMV gB. We have also recently shown that gB is localized to the
trans
-Golgi network (TGN) in HCMV-permissive cells, thereby identifying the TGN as a possible site of virus envelopment. The aim of the current study was to determine the role of Ser
900
phosphorylation in transport of gB to the TGN and in HCMV biogenesis. Recombinant HCMV strains were constructed that expressed gB molecules containing either an aspartic acid (gBAsp
900
) or alanine residue (gBAla
900
) substitution at Ser
900
to mimic the phosphorylated or nonphosphorylated form, respectively. Immunofluorescence analysis of the trafficking of gB mutant molecules in fibroblasts infected with the HCMV recombinants revealed that gBAsp
900
was localized to the TGN. In contrast, gBAla
900
was partially mislocalized from the TGN, indicating that phosphorylation of gB at Ser
900
was necessary for TGN localization. The increased TGN localization of gBAsp
900
was due to a decreased transport of the molecule to post-TGN compartments. Remarkably, the substitution of an aspartic acid residue for Ser
900
also resulted in an increase in levels of progeny virus production during HCMV infection of fibroblasts. Together, these results demonstrate that phosphorylation of gB at Ser
900
is necessary for gB localization to the TGN, as well as for efficient viral replication, and further support the TGN as a site of HCMV envelopment.
Selectively Receptor-Blind Measles Viruses: Identification of Residues Necessary for SLAM- or CD46-Induced Fusion and Their Localization on a New Hemagglutinin Structural Model
Authors: Vongpunsawad Sompong , Oezgun Numan , Braun Werner , Cattaneo Roberto 
Published: December 2003

ABSTRACTMeasles virus (MV) enters cells either through the signaling lymphocyte activation molecule SLAM (CD150) expressed only in immune cells or through the ubiquitously expressed regulator of complement activation, CD46. To identify residues on the attachment protein hemagglutinin (H) essential for fusion support through either receptor, we devised a strategy based on analysis of morbillivirus H-protein sequences, iterative cycles of mutant protein production followed by receptor-based functional assays, and a novel MV H three-dimensional model. This model uses the Newcastle disease virus hemagglutinin-neuraminidase protein structure as a template. We identified seven amino acids important for SLAM- and nine for CD46 (Vero cell receptor)-induced fusion. The MV H three-dimensional model suggests (i) that SLAM- and CD46-relevant residues are located in contiguous areas in propeller β-sheets 5 and 4, respectively; (ii) that two clusters of SLAM-relevant residues exist and that they are accessible for receptor contact; and (iii) that several CD46-relevant amino acids may be shielded from direct receptor contacts. It appears likely that certain residues support receptor-specific H-protein conformational changes. To verify the importance of the H residues identified with the cell-cell fusion assays for virus entry into cells, we transferred the relevant mutations into genomic MV cDNAs. Indeed, we were able to recover recombinant viruses, and we showed that these replicate selectively in cells expressing SLAM or CD46. Selectively receptor-blind viruses will be used to study MV pathogenesis and may have applications for the production of novel vaccines and therapeutics.