bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hypovirus Papain-Like Protease p29 Functions in
trans
To Enhance Viral Double-Stranded RNA Accumulation and Vertical Transmission
Authors: Suzuki Nobuhiro , Maruyama Kazuyuki , Moriyama Miho , Nuss Donald L. 
Published: October 2003

ABSTRACT

The prototypic hypovirus CHV1-EP713 attenuates virulence (hypovirulence) and alters several physiological processes of the chestnut blight fungus
Cryphonectria parasitica
. The papain-like protease, p29, and the highly basic protein, p40, derived, respectively, from the N-terminal and C-terminal portions of the CHV1-EP713-encoded open reading frame (ORF) A polyprotein, p69, both contribute to reduced pigmentation and sporulation. The p29 coding region was shown to suppress pigmentation and asexual sporulation in the absence of virus infection in transformed
C. parasitica
, whereas transformants containing the p40-coding domain exhibited a wild-type, untransformed phenotype. Deletion of either p29 or p40 from the viral genome also results in reduced accumulation of viral RNA. We now show that p29, but not p40, functions in
trans
to enhance genomic RNA accumulation and vertical transmission of p29 deletion mutant viruses. The frequency of virus transmission through conidia was found to decrease with reduced accumulation of viral genomic double-stranded RNA (dsRNA): from almost 100% for wild-type virus to ∼50% for Δp29, and 10 to 20% for Δp69. When expressed from a chromosomally integrated cDNA copy, p29 elevated viral dsRNA accumulation and transmission for Δp29 mutant virus to the level shown by wild-type virus. Increased viral RNA accumulation levels were also observed for a Δp69 mutant lacking almost the entire ORF A sequence. Such enhancements were not detected in transgenic fungal colonies expressing p40. Mutation of p29 residues Cys
70
or Cys
72
, strictly conserved in hypovirus p29 and potyvirus HC-Pro, resulted in the loss of both p29-mediated suppressive activity in virus-free transgenic
C. parasitica
and in
trans
enhancement of RNA accumulation and transmission, suggesting a linkage between these functional activities. These results suggest that p29 is an enhancer of viral dsRNA accumulation and vertical virus transmission through asexual spores.
Severe CD4+T-Cell Depletion in Gut Lymphoid Tissue during Primary Human Immunodeficiency Virus Type 1 Infection and Substantial Delay in Restoration following Highly Active Antiretroviral Therapy
Authors: Guadalupe Moraima , Reay Elizabeth , Sankaran Sumathi , Prindiville Thomas , Flamm Jason , McNeil Andrew , Dandekar Satya 
Published: October 2003

ABSTRACTGut-associated lymphoid tissue (GALT) harbors the majority of T lymphocytes in the body and is an important target for human immunodeficiency virus type 1 (HIV-1). We analyzed longitudinal jejunal biopsy samples from HIV-1-infected patients, during both primary and chronic stages of HIV-1 infection, prior to and following the initiation of highly active antiretroviral therapy (HAART) to determine the onset of CD4+T-cell depletion and the effect of HAART on the restoration of CD4+T cells in GALT. Severe depletion of intestinal CD4+T cells occurred during primary HIV-1 infection. Our results showed that the restoration of intestinal CD4+T cells following HAART in chronically HIV-1-infected patients was substantially delayed and incomplete. In contrast, initiation of HAART during early stages of infection resulted in near-complete restoration of intestinal CD4+T cells, despite the delay in comparison to peripheral blood CD4+T-cell recovery. DNA microarray analysis of gene expression profiles and flow-cytometric analysis of lymphocyte homing and cell proliferation markers demonstrated that cell trafficking to GALT and not local proliferation contributed to CD4+T-cell restoration. Evaluation of jejunal biopsy samples from long-term HIV-1-infected nonprogressors showed maintenance of normal CD4+T-cell levels in both GALT and peripheral blood. Our results demonstrate that near-complete restoration of mucosal immune system can be achieved by initiating HAART early in HIV-1 infection. Monitoring of the restoration and/or maintenance of CD4+T cells in GALT provides a more accurate assessment of the efficacy of antiviral host immune responses as well as HAART.
Array Analysis of Viral Gene Transcription during Lytic Infection of Cells in Tissue Culture with Varicella-Zoster Virus
Authors: Cohrs Randall J. , Hurley Michael P. , Gilden Donald H. 
Published: October 2003

ABSTRACT
Varicella-zoster virus (VZV), a neurotropic alphaherpesvirus, causes childhood chickenpox (varicella), becomes latent in dorsal root and autonomic ganglia, and reactivates decades later to cause shingles (zoster) and other neurologic complications. Although the sequence and configuration of VZV DNA have been determined, relatively little is known about viral gene expression in productively infected cells. This is in part because VZV is highly cell associated, and sufficient titers of cell-free virus for use in synchronizing infection do not develop. PCR-based transcriptional arrays were constructed to simultaneously determine the relative abundance of the ≈70 predicted VZV open reading frames (ORFs). Fragments (250 to 600 bp) from the 5′ and 3′ end of each ORF were PCR amplified and inserted into plasmid vectors. The virus DNA inserts were amplified, quantitated, and spotted onto nylon membranes. Probing the arrays with radiolabeled cDNA synthesized from VZV-infected cells revealed an increase in the magnitude of the expressed VZV genes from days 1 to 3 after low-multiplicity virus infection but little change in their relative abundance. The most abundant VZV transcripts mapped to ORFs 9/9A, 64, 33/33A, and 49, of which only ORF 9 corresponded to a previously identified structural gene. Array analysis also mapped transcripts to three large intergenic regions previously thought to be transcriptionally silent, results subsequently confirmed by Northern blot and reverse transcription-PCR analysis. Array analysis provides a formidable tool to analyze transcription of an important ubiquitous human pathogen.
The AIDS-Like Disease of CD4C/Human Immunodeficiency Virus Transgenic Mice Is Associated with Accumulation of Immature CD11bHiDendritic Cells
Authors: Poudrier Johanne , Weng Xiaoduan , Kay Denis G. , Hanna Zaher , Jolicoeur Paul 
Published: October 2003

ABSTRACTCD4C/human immunodeficiency virus (HIV) transgenic mice develop an AIDS-like disease. We used this model to study the effects of HIV-1 on dendritic cells (DC). We found a progressive decrease in total DC numbers in the lymph nodes, with a significant accumulation of CD11bHiDC. In the thymus, the recovery of transgenic CD8α+DC had a tendency to be lower. Spleen DC were augmented in the marginal zone. Transgenic DC showed a decreased capacity to present antigen in vitro, consistent with their reduced major histocompatibility complex class II expression and impaired maturation profile. The accumulation of immature DC may contribute to disease and may reflect an adaptive advantage for the virus by favoring its replication and preventing the generation of fully functional antiviral responses.
Oligodendrocyte-Specific Expression of Human Immunodeficiency Virus Type 1 Nef in Transgenic Mice Leads to Vacuolar Myelopathy and Alters Oligodendrocyte Phenotype In Vitro
Authors: Radja Fatiha , Kay Denis G. , Albrecht Steffen , Jolicoeur Paul 
Published: October 2003

ABSTRACT

Vacuolar myelopathy (VM) is a frequent central nervous system complication of human immunodeficiency virus type 1 (HIV-1) infection. We report here that transgenic (Tg) mice expressing even low levels of Nef in oligodendrocytes under the regulation of the myelin basic protein (MBP) promoter (MBP/HIV
Nef
) developed VM similar to the human disease in its appearance and topography. The spinal cords of these Tg mice showed lower levels of the myelin proteins MAG and CNPase and of the 21-kDa isoform of MBP prior to the development of vacuoles. In addition, Tg oligodendrocytes in primary in vitro cultures appeared morphologically more mature but, paradoxically, exhibited a less mature phenotype based on O4, O1, CNPase, and MBP staining. In particular, mature CNPase
+
MBP
+
Tg oligodendrocytes were less numerous than non-Tg oligodendrocytes. Therefore, Nef appears to affect the proper differentiation of oligodendrocytes. These data suggest that even low levels of Nef expression in human oligodendrocytes may be responsible for the development of VM in HIV-1-infected individuals.
Evidence against an Essential Role of COPII-Mediated Cargo Transport to the Endoplasmic Reticulum-Golgi Intermediate Compartment in the Formation of the Primary Membrane of Vaccinia Virus
Authors: Husain Matloob , Moss Bernard 
Published: October 2003

ABSTRACT

Vaccinia virus assembles two distinct lipoprotein membranes. The primary membrane contains nonglycosylated proteins, appears as crescents in the cytoplasm, and delimits immature and mature intracellular virions. The secondary or wrapping membrane contains glycoproteins, is derived from virus-modified trans-Golgi or endosomal cisternae, forms a loose coat around some intracellular mature virions, and becomes the envelope of extracellular virions. Although the mode of formation of the wrapping membrane is partially understood, we know less about the primary membrane. Recent reports posit that the primary membrane originates from the endoplasmic reticulum-Golgi intermediate compartment (ERGIC). According to this model, viral primary membrane proteins are cotranslationally inserted into the ER and accumulate in the ERGIC. To test the ERGIC model, we employed Sar1
H79G
, a dominant negative form of the Sar1 protein, which is an essential component of coatomer protein II (COPII)-mediated cargo transport from the ER to the ERGIC and other post-ER compartments. Overexpression of Sar1
H79G
by transfection or by a novel recombinant vaccinia virus with an inducible Sar1
H79G
gene resulted in retention of ERGIC 53 in the ER but did not interfere with localization of viral primary membrane proteins in factory regions or with formation of viral crescent membranes and infectious intracellular mature virions. Wrapping of intracellular mature virions and formation of extracellular virions did not occur, however, because some proteins that are essential for the secondary membrane were retained in the ER as a consequence of Sar1
H79G
overexpression. Our data argue against an essential role of COPII-mediated cargo transport and the ERGIC in the formation of the viral primary membrane. Instead, viral membranes may be derived directly from the ER or by a novel mechanism.
Metaphase Chromosome Tethering Is Necessary for the DNA Synthesis and Maintenance of
oriP
Plasmids but Is Insufficient for Transcription Activation by Epstein-Barr Nuclear Antigen 1
Authors: Sears John , Kolman John , Wahl Geoffrey M. , Aiyar Ashok 
Published: October 2003

ABSTRACT

Epstein-Barr Virus (EBV) infects resting B cells, within which it establishes latency as a stable, circular episome with only two EBV components, the
cis
element
oriP
and the latently expressed protein EBNA1. It is believed that EBNA1's ability to tether
oriP
episomes to metaphase chromosomes is required for its stable replication. We created fusions between the DNA-binding domain (DBD) of EBNA1 and the cellular chromatin-binding proteins HMGA1a and HMG1 to determine the minimal requirements for stable maintenance of an
oriP
-based episome. These two proteins differ in that HMGA1a can associate with metaphase chromosomes but HMG1 cannot. Interestingly, coinciding with metaphase chromosome association, HMGA1a-DBD but not HMG1-DBD supported both the transient replication and stable maintenance of
oriP
plasmids, with efficiencies quantitatively similar to that of EBNA1. However, HMGA1a-DBD activated transcription from EBNA1-dependent episomal reporter to only 20% of the level of EBNA1. Furthermore, EBNA1 but not HMGA1a-DBD activated transcription from a chromosomally integrated EBNA1-dependent transcription reporter. This indicates that EBNA1 possesses functional domains that support transcription activation independent of its ability to tether episomal
oriP
plasmids to cellular chromosomes. We provide evidence that metaphase chromosome tethering is a fundamental requirement for maintenance of an
oriP
plasmid but is insufficient for EBNA1 to activate transcription.
Active Borna Disease Virus Polymerase Complex Requires a Distinct Nucleoprotein-to-Phosphoprotein Ratio but No Viral X Protein
Authors: Schneider Urs , Naegele Melanie , Staeheli Peter , Schwemmle Martin 
Published: October 2003

ABSTRACT
Analysis of the composition and regulation of the Borna disease virus (BDV) polymerase complex has so far been limited by the lack of a functional assay. To establish such an assay on the basis of an artificial minigenome, we constructed expression vectors encoding either nucleoprotein (N), phosphoprotein (P), X protein, or polymerase (L) of BDV under the control of the chicken β-actin promoter. A Flag-tagged version of L colocalized with virus-encoded N and P in characteristic nuclear dots of BDV-infected cells and increased viral N-protein levels in persistently infected Vero cells. Vector-driven expression of L, N, and P in BSR-T7 cells together with a negative-sense BDV minigenome carrying a chloramphenicol acetyltransferase (CAT) reporter gene resulted in efficient synthesis of CAT protein. Induction of CAT protein synthesis strongly depended on a 10- to 30-fold molar excess of the N-encoding plasmid over the P-encoding plasmid. Cotransfection of even small amounts of plasmid encoding the viral X protein reduced CAT synthesis to background levels. Thus, the N-to-P stoichiometry seems to play a central role in the regulation of the BDV polymerase complex. Our data further suggest a negative regulatory function for the X protein of BDV.
Norwalk Virus Nonstructural Protein p48 Forms a Complex with the SNARE Regulator VAP-A and Prevents Cell Surface Expression of Vesicular Stomatitis Virus G Protein
Authors: Ettayebi Khalil , Hardy Michele E. 
Published: October 2003

ABSTRACT

Norwalk virus
(NV), a reference strain of human calicivirus in the
Norovirus
genus of the family
Caliciviridae
, contains a positive-strand RNA genome with three open reading frames. ORF1 encodes a 1,789-amino-acid polyprotein that is processed into nonstructural proteins that include an NTPase, VPg, protease, and RNA-dependent RNA polymerase. The N-terminal protein p48 of ORF1 shows no significant sequence similarity to viral or cellular proteins, and its function in the human calicivirus replication cycle is not known. The lack of sequence similarity to any protein in the public databases suggested that p48 may have a unique function in the NV replication cycle or, alternatively, may perform a characterized function in replication by a unique mechanism. In this report, it is shown that p48 displays a vesicular localization pattern in transfected cells when fused to the fluorescent reporter EYFP. A predicted transmembrane domain at the C terminus of p48 was not necessary for the observed localization pattern, but this domain was sufficient to redirect localization of EYFP to a fluorescent pattern consistent with the Golgi apparatus. A yeast two-hybrid screen identified the SNARE regulator vesicle-associated membrane protein-associated protein A (VAP-A) as a binding partner of p48. Biochemical assays confirmed that p48 and VAP-A interact and form a stable complex in mammalian cells. Furthermore, expression of the vesicular stomatitis virus G glcyoprotein on the cell surface was inhibited when cells coexpressed p48, suggesting that p48 disrupts intracellular protein trafficking.
Astrovirus Induces Diarrhea in the Absence of Inflammation and Cell Death
Authors: Koci Matthew D. , Moser Lindsey A. , Kelley Laura A. , Larsen Diane , Brown Corrie C. , Schultz-Cherry Stacey 
Published: October 2003

ABSTRACTAstroviruses are a leading cause of infantile viral gastroenteritis worldwide. Very little is known about the mechanisms of astrovirus-induced diarrhea. One reason for this is the lack of a small-animal model. Recently, we isolated a novel strain of astrovirus (TAstV-2) from turkeys with the emerging infectious disease poult enteritis mortality syndrome. In the present studies, we demonstrate that TAstV-2 causes growth depression, decreased thymus size, and enteric infection in infected turkeys. Infectious TAstV-2 can be recovered from multiple tissues, including the blood, suggesting that there is a viremic stage during infection. In spite of the severe diarrhea, histopathologic changes in the intestine were mild and there was a surprising lack of inflammation. This may be due to the increased activation of the potent immunosuppressive cytokine transforming growth factor beta during astrovirus infection. These studies suggest that the turkey will be a useful small-animal model with which to study astrovirus pathogenesis and immunity.
Adenovirus E1B 55-Kilodalton Oncoprotein Binds to Daxxand Eliminates Enhancement of p53-Dependent Transcription byDaxx
Authors: Zhao Lisa Y. , Colosimo April L. , Liu Yue , Wan Yanping , Liao Daiqing 
Published: October 2003

ABSTRACT
The
adenovirus E1B 55-kDa protein impairs the p53 pathway and enhances
transformation, although the underlying mechanisms remain to be
defined. We found that Daxx binds to the E1B 55-kDa protein in a yeast
two-hybrid screen. The two proteins interact through their C termini.
Mutation of three potential phosphorylation sites (S489/490 and T494 to
alanine) within the E1B 55-kDa protein did not affect its interaction
with Daxx, although such mutations were previously shown to inhibit
E1B's ability to repress p53-dependent transcription and to
enhance transformation. In addition to their coimmunoprecipitation in
293 extracts, purified Daxx interacted with the E1B 55-kDa protein in
vitro, indicating their direct interaction. In 293 cells, Daxx
colocalized with the E1B 55-kDa protein within discrete nuclear dots,
where p53 was also found. Such structures were distinct from PML
(promyelocytic leukemia protein) bodies, and it appeared that Daxx was
displaced from PML bodies. Thus, the Daxx concentration was diminished
in dots with a prominent presence of PML and vice versa. Indeed, PML
overexpression led to dramatic redistribution of Daxx from
p53-E1B 55-kDa protein complexes to PML bodies. Additionally,
expression of the E1B 55-kDa protein in Saos2 osteosarcoma cells
reduced the number of PML bodies. Our data suggest that E1B and PML
compete for available Daxx in the cell. Surprisingly, Daxx
significantly augmented p53-mediated transcription and the E1B 55-kDa
protein eliminated this effect. Thus, it is likely that the E1B 55-kDa
protein sequesters Daxx and p53 in specific nuclear locations, where
p53 cannot activate transcription. One consequence of the Daxx-E1B
interaction might be an alteration of normal interactions of Daxx, PML,
and p53, which may contribute to cell
transformation.
Dengue Virus Induces Novel Changes in Gene Expression of Human Umbilical Vein Endothelial Cells
Authors: Warke Rajas V. , Xhaja Kris , Martin Katherine J. , Fournier Marcia F. , Shaw Sunil K. , Brizuela Nathaly , de Bosch Norma , Lapointe David , Ennis Francis A. , Rothman Alan L. , Bosch Irene 
Published: October 2003

ABSTRACTEndothelial cells are permissive to dengue virus (DV) infection in vitro, although their importance as targets of DV infection in vivo remains a subject of debate. To analyze the virus-host interaction, we studied the effect of DV infection on gene expression in human umbilical vein endothelial cells (HUVECs) by using differential display reverse transcription-PCR (DD-RTPCR), quantitative RT-PCR, and Affymetrix oligonucleotide microarrays. DD identified eight differentially expressed cDNAs, including inhibitor of apoptosis-1, 2′-5′ oligoadenylate synthetase (OAS), a 2′-5′ OAS-like (OASL) gene, galectin-9, myxovirus protein A (MxA), regulator of G-protein signaling, endothelial and smooth muscle cell-derived neuropilin-like protein, and phospholipid scramblase 1. Microarray analysis of 22,000 human genes confirmed these findings and identified an additional 269 genes that were induced and 126 that were repressed more than fourfold after DV infection. Broad functional responses that were activated included the stress, defense, immune, cell adhesion, wounding, inflammatory, and antiviral pathways. These changes in gene expression were seen after infection of HUVECs with either laboratory-adapted virus or with virus isolated directly from plasma of DV-infected patients. Tumor necrosis factor alpha, OASL, and MxA and h-IAP1 genes were induced within the first 8 to 12 h after infection, suggesting a direct effect of DV infection. These global analyses of DV effects on cellular gene expression identify potentially novel mechanisms involved in dengue disease manifestations such as hemostatic disturbance.
The Hepatitis B Virus Polymerase Mutation rtV173L Is Selected during Lamivudine Therapy and Enhances Viral Replication In Vitro
Authors: Delaney William E. , Yang Huiling , Westland Christopher E. , Das Kalyan , Arnold Eddy , Gibbs Craig S. , Miller Michael D. , Xiong Shelly 
Published: October 2003

ABSTRACT
Therapy of chronic hepatitis B virus (HBV) infection with the polymerase inhibitor lamivudine frequently is associated with the emergence of viral resistance. Genotypic changes in the YMDD motif (reverse transcriptase [rt] mutations rtM204V/I) conferred resistance to lamivudine as well as reducing the in vitro replication efficiency of HBV. A second mutation, rtL180M, was previously reported to partially restore replication fitness as well as to augment drug resistance in vitro. Here we report the functional characterization of a third polymerase mutation (rtV173L) associated with resistance to lamivudine and famciclovir. rtV173L was observed at baseline in 9 to 22% of patients who entered clinical trials of adefovir dipivoxil for the treatment of lamivudine-resistant HBV. In these patients, rtV173L was invariably found as a third mutation in conjunction with rtL180M and rtM204V. In vitro analyses indicated that rtV173L did not alter the sensitivity of wild-type or lamivudine-resistant HBV to lamivudine, penciclovir, or adefovir but instead enhanced viral replication efficiency. A molecular model of HBV polymerase indicated that residue rtV173 is located beneath the template strand of HBV nucleic acid near the active site of the reverse transcriptase. Substitution of leucine for valine at this residue may enhance polymerization either by repositioning the template strand of nucleic acid or by affecting other residues involved in the polymerization reaction. Together, these results suggest that rtV173L is a compensatory mutation that is selected in lamivudine-resistant patients due to an enhanced replication phenotype.
Hendra Virus V Protein Inhibits Interferon Signaling by Preventing STAT1 and STAT2 Nuclear Accumulation
Authors: Rodriguez Jason J. , Wang Lin-Fa , Horvath Curt M. 
Published: October 2003

ABSTRACT

The V protein of the recently emerged paramyxovirus, Nipah virus, has been shown to inhibit interferon (IFN) signal transduction through cytoplasmic sequestration of cellular STAT1 and STAT2 in high-molecular-weight complexes. Here we demonstrate that the closely related Hendra virus V protein also inhibits cellular responses to IFN through binding and cytoplasmic sequestration of both STAT1 and STAT2, but not STAT3. These findings demonstrate a V protein-mediated IFN signal evasion mechanism that is a general property of the known
Henipavirus
species.