bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recruitment of Cellular Recombination and Repair Proteins to Sites of Herpes Simplex Virus Type 1 DNA Replication Is Dependent on the Composition of Viral Proteins within Prereplicative Sites and Correlates with the Induction of the DNA Damage Response
Authors: Wilkinson Dianna E. , Weller Sandra K. 
Published: April 2004

ABSTRACT
Herpes simplex virus type 1 (HSV-1) DNA replication is associated with nuclear domains called ND10, which contain host recombination proteins such as RPA, RAD51, and NBS1 and participate in the cell's response to DNA damage. The stages of HSV-1 infection have been described previously. Infected cells at stage IIIa are observed after the initial disruption of ND10 and display nuclear foci, or prereplicative sites, containing the viral single-stranded-DNA-binding protein (UL29), the origin-binding protein (UL9), and the heterotrimeric helicase-primase. At stage IIIb, the viral polymerase, its processivity factor, and the ND10, protein PML, are also recruited to these sites. In this work, RPA, RAD51, and NBS1 were observed predominantly in stage IIIb but not stage IIIa prereplicative sites, suggesting that the efficient recruitment of these recombination proteins is dependent on the presence of the viral polymerase and other replication proteins within these sites. On the other hand, Ku86 was not found in any of the precursors to replication compartments, suggesting that it is excluded from the early stages of HSV-1 replication. Western blot analysis showed that RPA and NBS1 were (hyper)phosphorylated during infection, indicating that infection induces the host response to DNA damage. Finally, RPA, RAD51, and NBS1 were found to be associated with UL29 foci observed in transfected cells expressing UL29 and the helicase-primase heterotrimer and containing intact ND10. The ability to recruit recombination and repair proteins to various subassemblies of viral replication proteins thus appears to depend on several factors, including the presence of the viral polymerase and/or UL9 within prereplicative sites and the integrity of ND10.
Increased Incidence of Squamous Cell Carcinomas in
Mastomys natalensis
Papillomavirus E6 Transgenic Mice during Two-Stage Skin Carcinogenesis
Authors: Helfrich Iris , Chen Min , Schmidt Rainer , Fürstenberger Gerhard , Kopp-Schneider Annette , Trick David , Gröne Hermann-Josef , zur Hausen Harald , Rösl Frank 
Published: April 2004

ABSTRACT

Papillomaviruses cause certain forms of human cancers, most notably carcinomas of the uterine cervix. In contrast to the well-established involvement of papillomavirus infection in the etiology of cervical carcinomas and in carcinomas of a rare hereditary condition, epidermodysplasia verruciformis, a causative role for cutaneous human papillomavirus types in the development of nonmelanoma skin cancer has not been proven. In order to better understand the functions of individual genes of cutaneous papillomavirus types, we generated transgenic mice carrying oncogene E6 of the
Mastomys natalensis
papillomavirus (MnPV), which causes keratoacanthomas of the skin in its natural host. In the present study, we demonstrate that under conditions of experimental two-stage skin carcinogenesis, fast-paced squamous cell carcinomas develop in nearly 100% of MnPV E6 transgenic mice in comparison to 10% in their nontransgenic littermates (log rank test;
P
< 0.0001). Therefore, we conclude that the MnPV E6 transgene favors the malignant progression of chemically induced tumors. Whereas an activating H-
ras
mutation is a consistent feature in benign and malignant tumors in wild-type mice, the majority of papillomas and keratoacanthomas and all squamous cell carcinomas obtained in MnPV E6 transgenic mice contain nonmutated
ras
alleles. These results indicate that the development of squamous cell carcinomas in MnPV E6 transgenic mice does not depend on an activated H-
ras
oncogene.
A Glycine-Rich Bovine Herpesvirus 5 (BHV-5) gE-Specific Epitope within the Ectodomain Is Important for BHV-5 Neurovirulence
Authors: Al-Mubarak A. , Zhou Y. , Chowdhury S. I. 
Published: April 2004

ABSTRACTThe bovine herpesvirus 5 (BHV-5) gE ectodomain contains a glycine-rich epitope coding region (gE5 epitope), residues 204 to 218, that is significantly different from the corresponding gE region of BHV-1. Deletion of the gE epitope significantly reduced the neurovirulence of BHV-5 in rabbits. Pulse-chase analyses revealed that the epitope-deleted and wild-type gE were synthesized as N-glycosylated endoglycosidase H-sensitive precursors with approximate molecular masses of 85 kDa and 86 kDa, respectively. Like the wild-type gE, epitope-deleted gE complexed with gI and was readily transported from the endoplasmic reticulum. Concomitantly, the epitope-deleted and wild-type gE acquired posttranslational modifications in the Golgi leading to an increased apparent molecular mass of 93-kDa (epitope-deleted gE) and 94-kDa (wild-type gE). The kinetics of mutant and wild-type gE processing were similar, and both mature proteins were resistant to endoglycosidase H but sensitive to glycopeptidase F. The gE epitope-deleted BHV-5 formed wild-type-sized plaques in MDBK cells, and the epitope-deleted gE was expressed on the cell surface. However, rabbits infected intranasally with gE epitope-deleted BHV-5 did not develop seizures, and only 20% of the infected rabbits showed mild neurological signs. The epitope-deleted virus replicated efficiently in the olfactory epithelium. However, within the brains of these rabbits there was a 10- to 20-fold reduction in infected neurons compared with the number of infected neurons within the brains of rabbits infected with the gE5 epitope-reverted and wild-type BHV-5. In comparison, 70 to 80% of the rabbits exhibited severe neurological signs when infected with the gE5 epitope-reverted and wild-type BHV-5. These results indicated that anterograde transport of the gE epitope-deleted virus from the olfactory receptor neurons to the olfactory bulb is defective and that, within the central nervous system, the gE5 epitope-coding region was required for expression of the full virulence potential of BHV-5.
A Novel Motif in Geminivirus Replication Proteins Interacts with the Plant Retinoblastoma-Related Protein
Authors: Arguello-Astorga Gerardo , Lopez-Ochoa Luisa , Kong Ling-Jie , Orozco Beverly M. , Settlage Sharon B. , Hanley-Bowdoin Linda 
Published: April 2004

ABSTRACT
The geminivirus replication factor AL1 interacts with the plant retinoblastoma-related protein (pRBR) to modulate host gene expression. The AL1 protein of tomato golden mosaic virus (TGMV) binds to pRBR through an 80-amino-acid region that contains two highly predicted α-helices designated 3 and 4. Earlier studies suggested that the helix 4 motif, whose amino acid sequence is strongly conserved across geminivirus replication proteins, plays a role in pRBR binding. We generated a series of alanine substitutions across helix 4 of TGMV AL1 and examined their impact on pRBR binding using yeast two-hybrid assays. These experiments showed that several helix 4 residues are essential for efficient pRBR binding, with a critical residue being a leucine at position 148 in the middle of the motif. Various amino acid substitutions at leucine-148 indicated that both structural and side chain components contribute to pRBR binding. The replication proteins of the geminiviruses tomato yellow leaf curl virus and cabbage leaf curl virus (CaLCuV) also bound to pRBR in yeast dihybrid assays. Mutation of the leucine residue in helix 4 of CaLCuV AL1 reduced binding. Together, these results suggest that helix 4 and the conserved leucine residue are part of a pRBR-binding interface in begomovirus replication proteins.
Norwalk Virus N-Terminal Nonstructural Protein Is Associated with Disassembly of the Golgi Complex in Transfected Cells
Authors: Fernandez-Vega Virneliz , Sosnovtsev Stanislav V. , Belliot Gaël , King Adriene D. , Mitra Tanaji , Gorbalenya Alexander , Green Kim Y. 
Published: April 2004

ABSTRACT

Norwalk virus
is the prototype strain for members of the genus
Norovirus
in the family
Caliciviridae
, which are associated with epidemic gastroenteritis in humans. The nonstructural protein encoded in the N-terminal region of the first open reading frame (ORF1) of the Norwalk virus genome is analogous in gene order to proteins 2A and 2B of the picornaviruses; the latter is known for its membrane-associated activities. Confocal microscopy imaging of cells transfected with a vector plasmid that provided expression of the entire Norwalk virus N-terminal protein (amino acids 1 to 398 of the ORF1 polyprotein) showed colocalization of this protein with cellular proteins of the Golgi apparatus. Furthermore, this colocalization was characteristically associated with a visible disassembly of the Golgi complex into discrete aggregates. Deletion of a predicted hydrophobic region (amino acids 360 to 379) in a potential 2B-like (2BL) region (amino acids 301 to 398) near the C terminus of the Norwalk virus N-terminal protein reduced Golgi colocalization and disassembly. Confocal imaging was conducted to examine the expression characteristics of fusion proteins in which the 2BL region from the N-terminal protein of Norwalk virus (a genogroup I norovirus) or MD145 (a genogroup II norovirus) was fused to the C terminus of enhanced green fluorescent protein. Expression of each fusion protein in cells showed evidence for its colocalization with the Golgi apparatus. These data indicate that the N-terminal protein of Norwalk virus interacts with the Golgi apparatus and may play a 2BL role in the induction of intracellular membrane rearrangements associated with positive-strand RNA virus replication in cells.
In Vitro Replication of Hepatitis E Virus (HEV) Genomes and of an HEV Replicon Expressing Green Fluorescent Protein
Authors: Emerson Suzanne U. , Nguyen Hanh , Graff Judith , Stephany David A. , Brockington Alicia , Purcell Robert H. 
Published: April 2004

ABSTRACT
Hepatitis E virus (HEV) RNA replication occurred in seven of nine primate cell cultures transfected with in vitro transcripts of an infectious cDNA clone. Cell-to-cell spread did not occur in cell cultures, but rhesus monkeys inoculated with lysates of HEV-transfected PLC/PRF/5 and Huh-7 cells became infected with HEV. A replicon with the ORF2 and ORF3 genes deleted and replaced with the green fluorescent protein gene also replicated in the same primate cells that supported the replication of the full-length genome. Fluorescence-activated cell sorter analysis confirmed that the 7mG cap structure was critical for efficient infectivity, although replication could be initiated at a very low level in its absence. HEV virions were also able to infect a limited number of cells of certain lines.
CCAAT/Enhancer Binding Protein α Binds to the Epstein-Barr Virus (EBV) ZTA Protein through Oligomeric Interactions and Contributes to Cooperative Transcriptional Activation of the ZTA Promoter through Direct Binding to the ZII and ZIIIB Motifs during Induction of the EBV Lytic Cycle
Authors: Wu Frederick Y. , Wang Shizhen Emily , Chen Honglin , Wang Ling , Hayward S. Diane , Hayward Gary S. 
Published: April 2004

ABSTRACT

The Epstein-Barr virus (EBV)-encoded ZTA protein interacts strongly with and stabilizes the cellular CCAAT/enhancer binding protein α (C/EBPα), leading to the induction of p21-mediated G
1
cell cycle arrest. Despite the strong interaction between these two basic leucine zipper (bZIP) family proteins, the ZTA and C/EBPα subunits do not heterodimerize, as indicated by an in vitro cross-linking assay with in vitro-cotranslated
35
S-labeled C/EBPα and
35
S-labeled ZTA protein. Instead, they evidently form a higher-order oligomeric complex that competes with C/EBPα binding but not with ZTA binding in electrophoretic mobility shift assays (EMSAs). Glutathione
S
-transferase affinity assays with mutant ZTA proteins revealed that the basic DNA binding domain and the key leucine zipper residues required for homodimerization are all required for the interaction with C/EBPα. ZTA is known to bind to two ZRE sites within the ZTA promoter and to positively autoregulate its own expression in transient cotransfection assays, but there is conflicting evidence about whether it does so in vivo. Examination of the proximal ZTA upstream promoter region by in vitro EMSA analysis revealed two high-affinity C/EBP binding sites (C-2 and C-3), which overlap the ZII and ZIIIB motifs, implicated as playing a key role in lytic cycle induction. A chromatin immunoprecipitation assay confirmed the in vivo binding of both endogenous C/EBPα and ZTA protein to the ZTA promoter after lytic cycle induction but not during the latent state in EBV-infected Akata cells. Reporter assays revealed that cotransfected C/EBPα activated the ZTA promoter even more effectively than cotransfected ZTA. However, synergistic activation of the ZTA promoter was not observed when ZTA and C/EBPα were cotransfected together in either HeLa or DG75 cells. Mutagenesis of either the ZII or the ZIIIB sites in the ZTA promoter strongly reduced C/EBPα transactivation, suggesting that these sites act cooperatively. Furthermore, the introduction of exogenous C/EBPα into EBV-infected HeLa-BX1 cells induced endogenous ZTA mRNA and protein expression, as demonstrated by both reverse transcription-PCR and immunoblotting assays. Finally, double-label immunofluorescence assays suggested that EAD protein expression was activated even better than ZTA expression in latently infected C/EBPα-transfected Akata cells, perhaps because of the presence of a strong B-cell-specific repressed chromatin conformation on the ZTA promoter itself during EBV latency.
Roles of Target Cells and Virus-Specific Cellular Immunity in Primary Simian Immunodeficiency Virus Infection
Authors: Regoes Roland R. , Antia Rustom , Garber David A. , Silvestri Guido , Feinberg Mark B. , Staprans Silvija I. 
Published: April 2004

ABSTRACTThere is an ongoing debate on whether acute human immunodeficiency virus infection is controlled by target cell limitation or by virus-specific cellular immunity. To resolve this question, we developed a novel mathematical modeling scheme which allows us to incorporate measurements of virus load, target cells, and virus-specific immunity and applied it to a comprehensive data set generated in an experiment involving rhesus macaques infected with simian immunodeficiency virus. Half of the macaques studied were treated during the primary infection period with reagents which block T-cell costimulation and as a result displayed severely impaired virus-specific immune responses. Our results show that early viral replication in normal infection is controlled to a large extent by virus-specific CD8+T cells and not by target cell limitation.
Characterization of a Highly Evolved Vaccine-Derived Poliovirus Type 3 Isolated from Sewage in Estonia
Authors: Blomqvist Soile , Savolainen Carita , Laine Pia , Hirttiö Päivi , Lamminsalo Elisa , Penttilä Eija , Jöks Silver , Roivainen Merja , Hovi Tapani 
Published: April 2004

ABSTRACT
Two types of vaccine-derived polioviruses have been recently designated to emphasize the different origins of the evolved viruses: circulating vaccine-derived polioviruses (cVDPV) associated with outbreaks of paralytic disease and strains isolated from chronically infected immunodeficient individuals (iVDPV). We describe here a type 3 VDPV (PV3/EST/02/E252; later E252) isolated from sewage collected in Tallinn, Estonia, in October 2002. Due to aberrant properties in subtyping, the virus was subjected to detailed characterization. Partial genomic sequencing suggested that the closest relative was the oral vaccine strain PV3/Sabin, but the two virus strains shared only 86.7% of the 900 nucleotides (nt) coding for the capsid protein VP1. Phylogenetic analysis of the nearly complete genome [nt 19 to poly(A)] revealed multiple nucleotide substitutions throughout the genome and a possible Sabin 3/Sabin 1-recombination junction site in the 2C coding region. A calculation based on the estimated mutation frequency of the P1 region of polioviruses suggested that the E252 virus might have replicated in one or more individuals for approximately 10 years. No persons chronically excreting poliovirus are known in Estonia. Amino acid substitutions were seen in all known antigenic sites, which was consistent with the observed aberrant antigenic properties of the virus demonstrated by both monoclonal antibodies and human sera from vaccinated children. In spite of the apparent transmission potential, no evidence was obtained for circulation of the virus in the Estonian population.
JC Virus Induces Nonapoptotic Cell Death of Human Central Nervous System Progenitor Cell-Derived Astrocytes
Authors: Seth Pankaj , Diaz Frank , Tao-Cheng Jung-Hwa , Major Eugene O. 
Published: April 2004

ABSTRACT
JC virus (JCV), a human neurotropic polyomavirus, demonstrates a selective glial cell tropism that causes cell death through lytic infection. Whether these cells die via apoptosis or necrosis following infection with JCV remains unclear. To investigate the mechanism of virus-induced cell death, we used a human central nervous system progenitor-derived astrocyte cell culture model developed in our laboratory. Using in situ DNA hybridization, immunocytochemistry, electron microscopy, and an RNase protection assay, we observed that astrocytes support a progressive JCV infection, which eventually leads to nonapoptotic cell death. Infected astrocyte cell cultures showed no difference from noninfected cells in mRNA expression of the caspase family genes or in any ultrastructural features associated with apoptosis. Infected cells demonstrated striking necrotic features such as cytoplasmic vacuolization, watery cytoplasm, and dissolution of organelles. Furthermore, staining for caspase-3 and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling were not detected in infected astrocyte cultures. Our findings suggest that JCV-induced cell death of these progenitor cell-derived astrocytes does not utilize an apoptosis pathway but exhibits a pattern of cell destruction consistent with necrotic cell death.
Reemerging H5N1 Influenza Viruses in Hong Kong in 2002 Are Highly Pathogenic to Ducks
Authors: Sturm-Ramirez Katharine M. , Ellis Trevor , Bousfield Barry , Bissett Lucy , Dyrting Kitman , Rehg Jerold E. , Poon Leo , Guan Yi , Peiris Malik , Webster Robert G. 
Published: April 2004

ABSTRACT
Waterfowl are the natural reservoir of all influenza A viruses, which are usually nonpathogenic in wild aquatic birds. However, in late 2002, outbreaks of highly pathogenic H5N1 influenza virus caused deaths among wild migratory birds and resident waterfowl, including ducks, in two Hong Kong parks. In February 2003, an avian H5N1 virus closely related to one of these viruses was isolated from two humans with acute respiratory distress, one of whom died. Antigenic analysis of the new avian isolates showed a reactivity pattern different from that of H5N1 viruses isolated in 1997 and 2001. This finding suggests that significant antigenic variation has recently occurred among H5N1 viruses. We inoculated mallards with antigenically different H5N1 influenza viruses isolated between 1997 and 2003. The new 2002 avian isolates caused systemic infection in the ducks, with high virus titers and pathology in multiple organs, particularly the brain. Ducks developed acute disease, including severe neurological dysfunction and death. Virus was also isolated at high titers from the birds' drinking water and from contact birds, demonstrating efficient transmission. In contrast, H5N1 isolates from 1997 and 2001 were not consistently transmitted efficiently among ducks and did not cause significant disease. Despite a high level of genomic homology, the human isolate showed striking biological differences from its avian homologue in a duck model. This is the first reported case of lethal influenza virus infection in wild aquatic birds since 1961.
Transduction of Terminally Differentiated Neurons by Avian Sarcoma Virus
Authors: Greger James G. , Katz Richard A. , Taganov Konstantin , Rall Glenn F. , Skalka Anna Marie 
Published: April 2004

ABSTRACT
Recent studies have demonstrated that avian sarcoma virus (ASV) can transduce cycle-arrested cells. Here, we have assessed quantitatively the transduction efficiency of an ASV vector in naturally arrested mouse hippocampal neurons. This efficiency was determined by comparing the number of transduced cells after infection of differentiated neurons versus dividing progenitor cells. The results indicate that ASV is able to transduce these differentiated neurons efficiently and that this activity is not the result of infection of residual dividing cells. The transduction efficiency of the ASV vector was found to be intermediate between the relatively high and low efficiencies obtained with human immunodeficiency virus type 1 and murine leukemia virus vectors, respectively.
A Human Immunodeficiency Virus Type 1-Infected Individual with Low Viral Load Harbors a Virus Variant That Exhibits an In Vitro RNA Dimerization Defect
Authors: Huthoff Hendrik , Das Atze T. , Vink Monique , Klaver Bep , Zorgdrager Fokla , Cornelissen Marion , Berkhout Ben 
Published: April 2004

ABSTRACT
We investigated the in vitro RNA dimerization properties of the untranslated leader RNA derived from human immunodeficiency virus type 1 variants circulating in an individual with a low viral load and slow disease progression. The leader sequences of these viruses contain highly unusual polymorphisms within the dimerization initiation site (DIS): an insert that abolishes dimerization and a compensatory substitution. The dimerization of leader RNA from late stages of infection is further improved by additional mutations outside the DIS motif that facilitate a secondary structure switch from a dimerization-incompetent to a dimerization-competent RNA conformation.
Delivery of Short Hairpin RNA Sequences by Using a Replication-Competent Avian Retroviral Vector
Authors: Bromberg-White Jennifer L. , Webb Craig P. , Patacsil Veronique S. , Miranti Cindy K. , Williams Bart O. , Holmen Sheri L. 
Published: April 2004

ABSTRACTWhile recent studies have demonstrated that retroviral vectors can be used to stably express short hairpin RNA (shRNA) to inhibit gene expression, these studies have utilized replication-defective retroviruses. We describe the creation of a replication-competent, Gateway-compatible retroviral vector capable of expressing shRNA that inhibits the expression of specific genes.
Inability of Simian Virus 40 To Establish Productive Infection of Lymphoblastic Cell Lines
Authors: Shaikh Sophie , Skoczylas Christine , Longnecker Richard , Rundell Kathleen 
Published: April 2004

ABSTRACT
Lymphoblastic cell lines were infected with simian virus 40 (SV40) and then monitored for evidence of a productive infection. No evidence of early gene expression was found 2 days following infection, as determined by assaying viral mRNAs and early antigens. Furthermore, only small amounts of virus could be detected by plaque assay 2 days after infection, and levels slowly declined until they were undetectable after a few weeks in culture. Thus, human lymphocytes are not readily infectible with SV40 and do not provide a simple model for studying interactions of SV40 with a human cell type.