bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Epstein-Barr Virus Immediate-Early Protein BZLF1 Induces both a G
2
and a Mitotic Block
Authors: Mauser Amy , Holley-Guthrie Elizabeth , Simpson Dennis , Kaufmann William , Kenney Shannon 
Published: September 2002

ABSTRACT

The Epstein-Barr virus immediate-early protein BZLF1 is a transcriptional activator that mediates the switch from latent to lytic infection. Here we demonstrate that BZLF1 induces both a G
2
block and a mitotic block in HeLa cells and inhibits chromosome condensation. While the G
2
block is associated with decreased cyclin B1 in host cells and can be rescued by overexpression of cyclin B1, the mechanism for the mitotic defect is as yet undetermined.
Sustained Peptide-Specific Gamma Interferon T-Cell Response in Rhesus Macaques Immunized with Human Immunodeficiency Virus
gag
DNA Vaccines
Authors: Caulfield Michael J. , Wang Su , Smith Jeffrey G. , Tobery Timothy W. , Liu Xu , Davies Mary-Ellen , Casimiro Danilo R. , Fu Tong-Ming , Simon Adam , Evans Robert K. , Emini Emilio A. , Shiver John 
Published: September 2002

ABSTRACT

We examined the influence of dose and method of antigen delivery on the dynamics and durability of T-cell responses to candidate human immunodeficiency virus (HIV) vaccines. Codon-optimized sequences from the HIV
gag
gene were inserted into alternative DNA vaccine vectors to express the coding sequence with or without the tissue plasminogen activator leader sequence. We delivered the vaccines by intramuscular injection as plasmid DNA without adjuvant or as plasmid DNA formulated with a novel block copolymer adjuvant (CRL8623) and then monitored the ensuing T-cell responses by using a gamma interferon enzyme-linked immunospot assay. We demonstrated persistence of the cell-mediated immune (CMI) response in rhesus macaques for at least 18 months following a four-dose vaccination regimen. The plasmid vaccine, with or without CRL8623, was immunogenic in macaques; however, the form coadministered with adjuvant exhibited improved T-cell responses, with a bias toward more antigen-specific CD8
+
T cells. Finally, we examined the fine specificity of the T-cell response to the
gag
vaccines by testing the response of 23 vaccinated macaques to individual Gag 20-mer peptides. Collectively, the monkeys responded to 25 epitopes, and, on average, each monkey recognized a minimum of 2.7 epitopes. The results indicate that a broad and durable CMI response to HIV DNA vaccines can be induced in a relevant nonhuman primate model.
Immune Responses to the Major Capsid Protein during Parvovirus Infection of Rats
Authors: Ball-Goodrich Lisa J. , Paturzo Frank X. , Johnson Elizabeth A. , Steger Krista , Jacoby Robert O. 
Published: September 2002

ABSTRACTRat virus (RV) is a common parvovirus of laboratory rodents which can disrupt rat-based research. Prenatal or perinatal infection can be pathogenic or lead to persistent infection, whereas infection of adult rats is typically self-limiting. Effects on the host immune system have been documented during RV infection, but little is known about immune responses necessary for viral clearance. Our studies were conducted to identify humoral and cellular responses to the predominant capsid protein, VP2, during experimental infection of adult rats. We observed VP2-specific proliferation, gamma interferon production, and an immunoglobulin G2a humoral response that is maintained for at least 35 days following RV infection. These results strongly suggest the induction of virus-specific Th1-mediated immunity.
Reversal by Dithiothreitol Treatment of the Block in Murine Leukemia Virus Maturation Induced by Disulfide Cross-Linking
Authors: Campbell Stephen , Oshima Masamichi , Mirro Jane , Nagashima Kunio , Rein Alan 
Published: September 2002

ABSTRACT
We previously reported that if murine leukemia virus particles are produced in the presence of the mild oxidizing agent disulfide-substituted benzamide-2, they fail to undergo the normal process of virus maturation. We now show that treatment of these immature particles with a reducing agent (dithiothreitol) induces their maturation in vitro, as evidenced by proteolytic cleavage of Gag, Gag-Pol, and Env proteins and by their morphology. The identification of partial cleavage products in these particles suggests the sequence with which the cleavages occur under these conditions. This may be a useful experimental system for further analysis of retroviral maturation under controlled conditions in vitro.
First Molecular Evidence for the Existence of Distinct Fish and Snake Adenoviruses
Authors: Benkő Mária , Élő Péter , Ursu Krisztina , Ahne Winfried , LaPatra Scott E. , Thomson Darelle , Harrach Balázs 
Published: September 2002

ABSTRACT

From adenovirus-like viruses originating from a fish and a snake species, a conserved part of the adenoviral DNA polymerase gene was PCR amplified, cloned and sequenced. Phylogenetic analysis showed that the snake adenovirus is closely related to the members of the proposed genus
Atadenovirus
, whereas the fish isolate seems to represent a separate cluster, likely a new genus.
A Hepatitis B Surface Antigen Mutant That Lacks the Antigenic Loop Region Can Self-Assemble and Interact with the Large Hepatitis Delta Antigen
Authors: O'Malley Brendan , Lazinski David 
Published: September 2002

ABSTRACT
A novel hepatitis B virus surface antigen mutant harboring a deletion of most of the major antigenic loop region was competent for self-assembly and secretion. Although the mutant protein was competent for interaction with and incorporation of free large hepatitis delta antigen, it was partially defective in hepatitis delta virus RNP incorporation.
Detection and Analysis of Hepatitis C Virus Sequences in Cerebrospinal Fluid
Authors: Laskus Tomasz , Radkowski Marek , Bednarska Agnieszka , Wilkinson Jeffrey , Adair Debra , Nowicki Marek , Nikolopoulou Georgia B. , Vargas Hugo , Rakela Jorge 
Published: September 2002

ABSTRACTHepatitis C virus (HCV) sequences were detected in cerebrospinal fluid (CSF) in 8 of 13 HCV-positive patients. In four patients harboring different virus strains in serum and peripheral blood mononuclear cells (PBMC), CSF-derived virus was similar to that found in PBMC, which suggests that PBMC could carry HCV into the brain.
Pregenomic RNA Is Required for Efficient Incorporation of Pol Polyprotein into Foamy Virus Capsids
Authors: Heinkelein Martin , Leurs Cordula , Rammling Matthias , Peters Katrin , Hanenberg Helmut , Rethwilm Axel 
Published: September 2002

ABSTRACT
The foamy virus (FV) Pol polyprotein is translated independently of Gag from a spliced mRNA. This method of expression raises the question of how Pol is associated with the viral particle. Using a transient FV vector transfection system, it is shown that pregenomic RNA is required for efficient virion incorporation of functionally active Pol and that protein-protein interactions of Pol with Gag are not sufficient to complete particle assembly.
Asian Genotypes of JC Virus in Japanese-Americans Suggest Familial Transmission
Authors: Suzuki Makoto , Zheng Huai-Ying , Takasaka Tomokazu , Sugimoto Chie , Kitamura Tadaichi , Beutler Ernest , Yogo Yoshiaki 
Published: September 2002

ABSTRACT
To examine the mode of JC virus (JCV) transmission, we collected urine samples from second- and third-generation Japanese-Americans in Los Angeles, Calif., whose parents and grandparents were all Japanese. From the urine samples of these Japanese-Americans, we mainly detected two subtypes (CY and MY) of JCV that are predominantly found among native Japanese. This finding provides support for the hypothesis that JCV is transmitted mainly within the family through long-term cohabitation.
Inhibition of Herpes Simplex Virus Replication by WAY-150138: Assembly of Capsids Depleted of the Portal and Terminase Proteins Involved in DNA Encapsidation
Authors: Newcomb William W. , Brown Jay C. 
Published: September 2002

ABSTRACT

Studies were carried out to examine the mechanism of action of WAY-150138, a member of a novel group of thiourea compounds recently shown to inhibit replication of herpes simplex virus type 1 (HSV-1). Previous studies have shown that the drug acts by preventing DNA encapsidation and that resistant mutants map to

U
L

6
, the gene encoding the protein subunit of the portal complex through which DNA enters the capsid. We tested the idea that WAY-150138 acts by preventing the incorporation of DNA-packaging proteins into capsids as they are assembled. Capsids were isolated from HSV-1-infected, drug-treated cells and examined by Western immunoblotting for the presence of two packaging proteins, the portal subunit (U
L
6) and a candidate terminase subunit (U
L
15). The results showed that both proteins were depleted in the capsids, suggesting that WAY-150138 antagonizes DNA encapsidation by depriving capsids of packaging proteins during the assembly process.
Secondary Structure and Hybridization Accessibility of Hepatitis C Virus 3′-Terminal Sequences
Authors: Smith Robert M. , Walton Cherie M. , Wu Catherine H. , Wu George Y. 
Published: September 2002

ABSTRACT

The 3′-terminal sequences of hepatitis C virus (HCV) positive- and negative-strand RNAs contribute
cis
-acting functions essential for viral replication. The secondary structure and protein-binding properties of these highly conserved regions are of interest not only for the further elucidation of HCV molecular biology, but also for the design of antisense therapeutic constructs. The RNA structure of the positive-strand 3′ untranslated region has been shown previously to influence binding by various host and viral proteins and is thus thought to promote HCV RNA synthesis and genome stability. Recent studies have attributed analogous functions to the negative-strand 3′ terminus. We evaluated the HCV negative-strand secondary structure by enzymatic probing with single-strand-specific RNases and thermodynamic modeling of RNA folding. The accessibility of both 3′-terminal sequences to hybridization by antisense constructs was evaluated by RNase H cleavage mapping in the presence of combinatorial oligodeoxynucleotide libraries. The mapping results facilitated identification of antisense oligodeoxynucleotides and a 10-23 deoxyribozyme active against the positive-strand 3′-X region RNA in vitro.
Vaccinia Virus J1R Protein: a Viral Membrane Protein That Is Essential for Virion Morphogenesis
Authors: Chiu Wen-Ling , Chang Wen 
Published: September 2002

ABSTRACT

Vaccinia virus
, a member of the poxvirus family, contains a conserved J1R open reading frame that encodes a late protein of 17.8 kDa. The 18-kDa J1R protein is associated mainly with the membrane fraction of intracellular mature virus particles. This study examines the biological function of J1R protein in the vaccinia virus life cycle. A recombinant vaccinia virus was constructed to conditionally express J1R protein in an isopropyl-β-
d
-galactopyranoside (IPTG)-inducible manner. When J1R is not expressed during vaccinia virus infection, the virus titer is reduced approximately 100-fold. In contrast, J1R protein is not required for viral gene expression, as indicated by protein pulse-labeling. J1R protein is also not required for DNA processing, as the resolution of the concatemer junctions of replicated viral DNA was detected without IPTG. A deficiency of J1R protein caused a severe delay in the processing of p4a and p4b into mature core proteins 4a and 4b, indicating that J1R protein participates in virion morphogenesis. Infected cells grown in the absence of IPTG contained very few intracellular mature virions in the cytoplasm, and enlarged viroplasm structures accumulated with viral crescents attached at the periphery. Abundant intermediate membrane structures of abnormal shapes were observed, and many immature virions were either empty or partially filled, indicating that J1R protein is important for DNA packaging into immature virions. J1R protein also coimmunoprecipited with A45R protein in infected cells. In summary, these results indicate that vaccinia virus J1R is a membrane protein that is required for virus growth and plaque formation. J1R protein interacts with A45R protein and performs an important role during immature virion formation in cultured cells.
Replication of a Cytopathic Strain of Bovine Viral Diarrhea Virus Activates PERK and Induces Endoplasmic Reticulum Stress-Mediated Apoptosis of MDBK Cells
Authors: Jordan Robert , Wang Lijuan , Graczyk Thomas M. , Block Timothy M. , Romano Patrick R. 
Published: September 2002

ABSTRACT

Endoplasmic reticulum (ER) stress signaling is an adaptive cellular response to the loss of ER Ca
2+
homeostasis and/or the accumulation of misfolded, unassembled, or aggregated proteins in the ER lumen. ER stress-activated signaling pathways regulate protein synthesis initiation and can also trigger apoptosis through the ER-associated caspase 12. Viruses that utilize the host cell ER as an integral part of their life cycle would be predicted to cause some level of ER stress. Bovine viral diarrhea virus (BVDV) is a positive-stranded RNA virus of the
Flaviviridae
family. BVDV and related flaviviruses use the host ER as the primary site of envelope glycoprotein biogenesis, genomic replication, and particle assembly. We are using a cytopathic strain of BVDV (cpBVDV) that causes cellular apoptosis as a model system to determine how virus-induced ER stress contributes to pathogenesis. We show that, in a natural infection of MDBK cells, cpBVDV activates the ER transmembrane kinase PERK (PKR-like ER kinase) and causes hyperphosphorylation of the translation initiation factor eIF2α, consistent with the induction of an ER stress response. Additionally, we show that initiation of cellular apoptosis correlates with downregulation of the antiapoptotic Bcl-2 protein, induced expression of caspase 12, and a decrease in intracellular glutathione levels. Defining the molecular stress pathways leading to cpBVDV-induced apoptosis provides the basis to study how other ER-tropic viruses, such as hepatitis C and B viruses, modulate the host cell ER stress response during the course of persistent infection.
In Vitro Intersubtype Recombinants of Human Immunodeficiency Virus Type 1: Comparison to Recent and Circulating In Vivo Recombinant Forms
Authors: Quiñones-Mateu Miguel E. , Gao Yong , Ball Sarah C. , Marozsan Andre J. , Abraha Awet , Arts Eric J. 
Published: September 2002

ABSTRACT

The increased prevalence of human immunodeficiency virus type 1 (HIV-1) intersubtype recombinants (ISRs) is shaping HIV-1 evolution throughout the world and will have an impact on both therapeutic and vaccine strategies. This study was designed to generate and compare in vitro ISRs to those isolated from HIV-infected individuals throughout the world. Human peripheral blood mononuclear cells were dually infected with seven pairs of HIV-1 isolates from different subtypes (i.e., A to F). Recombinant crossover sites were mapped to specific regions in the envelope (
env
) gene by using a cloning-hybridization technique and subtype-specific probes. In vitro intersubtype recombination was at least twofold more frequent in the V1-to-V3 region than in any other
env
fragment, i.e., C1 to V1, V3 to V5, or V5 to gp41. Sequence and recombination site analyses suggested the C2
env
domain as a “hot region” for recombination and selection of replication-competent ISRs during the 15-day incubation. In addition to these regional preferences for
env
recombination, homopolymeric nucleotide tracts, i.e., sequences known to pause reverse transcriptase and promote template switching, were found in most in vitro crossover sites. ISRs, originating from recent dual infections and limited transmission events, partly retained this in vitro regional or sequence preference for recombination sites. However, a shift to crossover sites flanking the gp120-coding sequence was evident in the stable circulating recombinant forms of HIV-1. Based on these findings, HIV-1 recombinants generated from these dual infections may be used as a model for in vivo intersubtype recombination and for the design of various diagnostic assays and vaccine constructs.
Intramolecular Recombinations of Moloney Murine Leukemia Virus Occur during Minus-Strand DNA Synthesis
Authors: Li Ting , Zhang Jiayou 
Published: September 2002

ABSTRACT
Retroviral recombination can occur between two viral RNA molecules (intermolecular) or between two sequences within the same RNA molecule (intramolecular). The rate of retroviral intramolecular recombination is high. Previous studies showed that, after a single round of replication, 50 to 60% of retroviral recombinations occur between two identical sequences within a Moloney murine leukemia virus-based vector. Recombination can occur at any polymerization step within the retroviral replication cycle. Although reverse transcriptase is assumed to contribute to the template switches, previous studies could not distinguish between changes introduced by host RNA polymerase II (Pol II) or by reverse transcriptase. A cell culture system has been established to detect the individual contribution of host RNA Pol II, host DNA polymerase or viral reverse transcriptase, as well as the recombination events taking place during minus-strand DNA synthesis and plus-strand DNA synthesis in a single round of viral intramolecular replication. Studies in this report demonstrate that intramolecular recombination between two identical sequences during transcription by host RNA Pol II is minimal and that most recombinations occur during minus-strand DNA synthesis catalyzed by viral reverse transcriptase.
Feline Immunodeficiency Virus OrfA Is Distinct from Other Lentivirus Transactivators
Authors: Chatterji Udayan , de Parseval Aymeric , Elder John H. 
Published: September 2002

ABSTRACT
The feline immunodeficiency virus (FIV) accessory factor, OrfA, facilitates transactivation of transcription directed by elements of the viral long terminal repeat (LTR). In order to map OrfA domains required for this transactivation, we used N- and C-terminal deletion constructs of the protein, expressed in a Gal4-based transactivation system. The results demonstrated that FIV OrfA, unlike other lentiviral transactivators such as visna virus Tat, is unable to transactivate from minimal promoter-based reporters and requires additional elements of the viral LTR. Stable CrFK-based cell lines were prepared that expressed OrfA to readily detectable levels and in which we were able to demonstrate 32-fold transactivation of an LTR-chloramphenicol acetyltransferase construct. Transactivation was heavily dependent on the presence of an ATF site within the viral LTR. Changing the translation initiation codon context substantially increased the level of production of OrfA from a bicistronic message that also encodes Rev. In the presence of a more favorable context sequence, the upstream expression of OrfA increased 21-fold, with only a 0.5-fold drop in downstream Rev expression. This suggests that Rev translation may occur via an internal ribosomal entry site rather than by leaky scanning.
Epstein-Barr Virus mRNA Export Factor EB2 Is Essential for Production of Infectious Virus
Authors: Gruffat Henri , Batisse Julien , Pich Dagmar , Neuhierl Bernhard , Manet Evelyne , Hammerschmidt Wolfgang , Sergeant Alain 
Published: September 2002

ABSTRACT

The splicing machinery which positions a protein export complex near the exon-exon junction mediates nuclear export of mRNAs generated from intron-containing genes. Many Epstein-Barr virus (EBV) early and late genes are intronless, and an alternative pathway, independent of splicing, must export the corresponding mRNAs. Since the EBV EB2 protein induces the cytoplasmic accumulation of intronless mRNA, it is tempting to speculate that EB2 is a viral adapter involved in the export of intronless viral mRNA. If this is true, then the EB2 protein is essential for the production of EBV infectious virions. To test this hypothesis, we generated an EBV mutant in which the BMLF1 gene, encoding the EB2 protein, has been deleted (EBV
BMLF1-KO
). Our studies show that EB2 is necessary for the production of infectious EBV and that its function cannot be transcomplemented by a cellular factor. In the EBV
BMLF1-KO
293 cells,
oriLyt
-dependent DNA replication was greatly enhanced by EB2. Accordingly, EB2 induced the cytoplasmic accumulation of a subset of EBV early mRNAs coding for essential proteins implicated in EBV DNA replication during the productive cycle. Two herpesvirus homologs of the EB2 protein, the herpes simplex virus type 1 protein ICP27 and, the human cytomegalovirus protein UL69, only partly rescued the phenotype of the EBV
BMLF1-KO
mutant, indicating that some EB2 functions in virus production cannot be transcomplemented by ICP27 and UL69.
Identification of Epstein-Barr Virus Strain Variants in Hairy Leukoplakia and Peripheral Blood by Use of a Heteroduplex Tracking Assay
Authors: Sitki-Green Diane , Edwards Rachel H. , Webster-Cyriaque Jennifer , Raab-Traub Nancy 
Published: September 2002

ABSTRACT
Epstein-Barr virus (EBV) strains can be distinguished by specific sequence variations in the LMP1 gene. In this study, a heteroduplex tracking assay (HTA) specific for LMP1 was developed to precisely identify the prototypic undeleted strain B958, other undeleted strains (Ch2, AL, NC, and Med−), and strains with the 30-bp deletion (Med+ and Ch1). This technique also provides an estimate of the relative abundance of strains in patient samples. In this study, EBV strains were identified in 25 hairy leukoplakia (HLP) biopsies and six matched peripheral blood samples and throat washes with the LMP1-HTA. To investigate the relationship of the virus found in the peripheral blood to that in the HLP lesion, the strain variants in the peripheral blood B lymphocytes and those present within the epithelial cells in the HLP lesion and in throat washes were identified. In many of the subjects, compartmental differences in the EBV strain profiles in the oral cavity and peripheral blood were readily apparent. The throat wash specimens usually had a strain profile similar to that within the corresponding HLP sample, which was distinct from the strain profile detected in the peripheral blood. These analyses reveal that the nature of EBV infection can be very dynamic, with changes in relative strain abundance over time as well as the appearance of new strains. The patterns of abundance in the blood and oral cavity provide evidence for compartmentalization and for the transmission of strains between the blood and oropharynx.