bluuebunny/crossref_metadata_2025_split huggingface dataset:
Herpes Simplex Virus 1

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31
and

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34
Gene Products Promote the Late Maturation of Viral Replication Compartments to the Nuclear Periphery
Authors: Simpson-Holley Martha , Baines Joel , Roller Richard , Knipe David M. 
Published: May 2004

ABSTRACT

Herpes simplex virus 1 (HSV-1) forms replication compartments (RCs), domains in which viral DNA replication, late-gene transcription, and encapsidation take place, in the host cell nucleus. The formation of these domains leads to compression and marginalization of host cell chromatin, which forms a dense layer surrounding the viral RCs and constitutes a potential barrier to viral nuclear egress or primary envelopment at the inner nuclear membrane. Surrounding the chromatin layer is the nuclear lamina, a further host cell barrier to egress. In this study, we describe an additional phase in RC maturation that involves disruption of the host chromatin and nuclear lamina so that the RC can approach the nuclear envelope. During this phase, the structure of the chromatin layer is altered so that it no longer forms a continuous layer around the RCs but instead is fragmented, forming islands between which RCs extend to reach the nuclear periphery. Coincident with these changes, the nuclear lamina components lamin A/C and lamin-associated protein 2 appear to be redistributed via a mechanism involving the

U
L

31
and

U
L

34
gene products. Viruses in which the

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L

31
or

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L

34
gene has been deleted are unable to undergo this phase of chromatin reorganization and lamina alterations and instead form RCs which are bounded by an intact host cell chromatin layer and nuclear lamina. We postulate that these defects in chromatin restructuring and lamina reorganization explain the previously documented growth defects of these mutant viruses.
Parvovirus Infection of Cells by Using Variants of the Feline Transferrin Receptor Altering Clathrin-Mediated Endocytosis, Membrane Domain Localization, and Capsid-Binding Domains
Authors: Hueffer Karsten , Palermo Laura M. , Parrish Colin R. 
Published: May 2004

ABSTRACT
The feline and canine transferrin receptors (TfRs) bind canine parvovirus to host cells and mediate rapid capsid uptake and infection. The TfR and its ligand transferrin have well-described pathways of endocytosis and recycling. Here we tested several receptor-dependent steps in infection for their role in virus infection of cells. Deletions of cytoplasmic sequences or mutations of the Tyr-Thr-Arg-Phe internalization motif reduced the rate of receptor uptake from the cell surface, while polar residues introduced into the transmembrane sequence resulted in increased degradation of transferrin. However, the mutant receptors still mediated efficient virus infection. In contrast, replacing the cytoplasmic and transmembrane sequences of the feline TfR with those of the influenza virus neuraminidase (NA) resulted in a receptor that bound and endocytosed the capsid but did not mediate viral infection. This chimeric receptor became localized to detergent-insoluble membrane domains. To test the effect of structural virus receptor interaction on infection, two chimeric receptors were prepared which contained antibody-variable domains that bound the capsid in place of the TfR ectodomain. These chimeric receptors bound CPV capsids and mediated uptake but did not result in cell infection. Adding soluble feline TfR ectodomain to the virus during that uptake did not allow infection.
Nipah Virus V and W Proteins Have a Common STAT1-Binding Domain yet Inhibit STAT1 Activation from the Cytoplasmic and Nuclear Compartments, Respectively
Authors: Shaw Megan L. , García-Sastre Adolfo , Palese Peter , Basler Christopher F. 
Published: May 2004

ABSTRACT

In previous reports it was demonstrated that the Nipah virus V and W proteins have interferon (IFN) antagonist activity due to their ability to block signaling from the IFN-α/β receptor (J. J. Rodriguez, J. P. Parisien, and C. M. Horvath, J. Virol.
76:
11476-11483, 2002; M. S. Park et al., J. Virol.
77:
1501-1511, 2003). The V, W, and P proteins are all encoded by the same viral gene and share an identical 407-amino-acid N-terminal region but have distinct C-terminal sequences. We now show that the P protein also has anti-IFN function, confirming that the common N-terminal domain is responsible for the antagonist activity. Truncation of this N-terminal domain revealed that amino acids 50 to 150 retain the ability to block IFN and to bind STAT1, a key component of the IFN signaling pathway. Subcellular localization studies demonstrate that the V and P proteins are predominantly cytoplasmic whereas the W protein is localized to the nucleus. In all cases, STAT1 colocalizes with the corresponding Nipah virus protein. These interactions are sufficient to inhibit STAT1 activation, as demonstrated by the lack of STAT1 phosphorylation on tyrosine 701 in IFN-stimulated cells expressing P, V, or W. Therefore, despite their common STAT1-binding domain, the Nipah virus V and P proteins act by retaining STAT1 in the cytoplasm while the W protein sequesters STAT1 in the nucleus, creating both a cytoplasmic and a nuclear block for STAT1. We also show that the IFN antagonist activity of the P protein is not as strong as that of V or W, perhaps explaining why Nipah virus has evolved to express these two edited products.
pH-Dependent Entry of Severe Acute Respiratory Syndrome Coronavirus Is Mediated by the Spike Glycoprotein and Enhanced by Dendritic Cell Transfer through DC-SIGN
Authors: Yang Zhi-Yong , Huang Yue , Ganesh Lakshmanan , Leung Kwanyee , Kong Wing-Pui , Schwartz Owen , Subbarao Kanta , Nabel Gary J. 
Published: May 2004

ABSTRACT
The severe acute respiratory syndrome coronavirus (SARS-CoV) synthesizes several putative viral envelope proteins, including the spike (S), membrane (M), and small envelope (E) glycoproteins. Although these proteins likely are essential for viral replication, their specific roles in SARS-CoV entry have not been defined. In this report, we show that the SARS-CoV S glycoprotein mediates viral entry through pH-dependent endocytosis. Further, we define its cellular tropism and demonstrate that virus transmission occurs through cell-mediated transfer by dendritic cells. The S glycoprotein was used successfully to pseudotype replication-defective retroviral and lentiviral vectors that readily infected Vero cells as well as primary pulmonary and renal epithelial cells from human, nonhuman primate, and, to a lesser extent, feline species. The tropism of this reporter virus was similar to that of wild-type, replication-competent SARS-CoV, and binding of purified S to susceptible target cells was demonstrated by flow cytometry. Although myeloid dendritic cells were able to interact with S and to bind virus, these cells could not be infected by SARS-CoV. However, these cells were able to transfer the virus to susceptible target cells through a synapse-like structure. Both cell-mediated infection and direct infection were inhibited by anti-S antisera, indicating that strategies directed toward this gene product are likely to confer a therapeutic benefit for antiviral drugs or the development of a SARS vaccine.
Murine Coronavirus Replication Induces Cell Cycle Arrest in G0/G1Phase
Authors: Chen Chun-Jen , Makino Shinji 
Published: May 2004

ABSTRACTMouse hepatitis virus (MHV) replication in actively growing DBT and 17Cl-1 cells resulted in the inhibition of host cellular DNA synthesis and the accumulation of infected cells in the G0/G1phase of the cell cycle. UV-irradiated MHV failed to inhibit host cellular DNA synthesis. MHV infection in quiescent 17Cl-1 cells that had been synchronized in the G0phase by serum deprivation prevented infected cells from entering the S phase after serum stimulation. MHV replication inhibited hyperphosphorylation of the retinoblastoma protein (pRb), the event that is necessary for cell cycle progression through late G1and into the S phase. While the amounts of the cellular cyclin-dependent kinase (Cdk) inhibitors p21Cip1, p27Kip1, and p16INK4adid not change in infected cells, MHV infection in asynchronous cultures induced a clear reduction in the amounts of Cdk4 and G1cyclins (cyclins D1, D2, D3, and E) in both DBT and 17Cl-1 cells and a reduction in Cdk6 levels in 17Cl-1 cells. Infection also resulted in a decrease in Cdk2 activity in both cell lines. MHV infection in quiescent 17Cl-1 cells prevented normal increases in Cdk4, Cdk6, cyclin D1, and cyclin D3 levels after serum stimulation. The amounts of cyclin D2 and cyclin E were not increased significantly after serum stimulation in mock-infected cells, whereas they were decreased in MHV-infected cells, suggesting the possibility that MHV infection may induce cyclin D2 and cyclin E degradation. Our data suggested that a reduction in the amounts of G1cyclin-Cdk complexes in MHV-infected cells led to a reduction in Cdk activities and insufficient hyperphosphorylation of pRb, resulting in inhibition of the cell cycle in the G0/G1phase.
A Bunyamwera Virus Minireplicon System in Mosquito Cells
Authors: Kohl Alain , Hart Timothy J. , Noonan Carol , Royall Elizabeth , Roberts Lisa O. , Elliott Richard M. 
Published: May 2004

ABSTRACT

Artificial minigenomes are powerful tools for studying the replication and transcription of negative-strand RNA viruses.
Bunyamwera virus
(BUN; genus
Orthobunyavirus
, family
Bunyaviridae
) is an arbovirus that shows fundamental biological differences when replicating in mammalian versus mosquito cells. To study BUN RNA synthesis in mosquito cells, we developed a bacteriophage T7 RNA polymerase-based minireplicon system similar to that described previously for mammalian cells. An
Aedes albopictus
C6/36-derived mosquito cell line stably expressing T7 RNA polymerase was established. Viral proteins and artificial minigenomes (containing
Renilla
luciferase as a reporter) were transcribed and expressed in these cells from transfected T7 promoter-containing plasmids. Transcription of the minigenome required two viral proteins, the nucleocapsid protein N and the RNA-dependent RNA polymerase L, a situation similar to that in mammalian cells. However, unlike the situation in mammalian cells, the viral polymerase was not inhibited by the viral nonstructural protein NSs. We also report that promoter strength is different for vertebrate versus invertebrate cells. The development of this system opens the way for a detailed comparison of bunyavirus replication in cells of disparate phylogeny.
Longitudinal Analysis of CD8+T Cells Specific for Structural and Nonstructural Hepatitis B Virus Proteins in Patients with Chronic Hepatitis B: Implications for Immunotherapy
Authors: Webster George J. M. , Reignat Stephanie , Brown David , Ogg Graham S. , Jones Louise , Seneviratne Suranjith L. , Williams Roger , Dusheiko Geoffrey , Bertoletti Antonio 
Published: May 2004

ABSTRACTThe cytotoxic T-cell response in chronic hepatitis B virus (HBV) infection has been described as weak and mono- or oligospecific in comparison to the more robust virus-specific T-cell response present in resolved infection. However, chronic hepatitis B is a heterogeneous disease with markedly variable levels of virus replication and liver disease activity. Here we analyzed (both directly ex vivo and after in vitro stimulation) the HBV-specific CD8 T-cell responses against structural and nonstructural HBV proteins longitudinally in patients with different patterns of chronic infections. We found that the profiles of virus-specific CD8+-T-cell responses during chronic infections are highly heterogeneous and influenced more by the level of HBV replication than by the activity of liver disease. An HBV DNA load of <107copies/ml appears to be the threshold below which circulating multispecific HBV-specific CD8+T cells are consistently detected. Furthermore, CD8+T cells with different specificities are differentially regulated during chronic infections. HBV core-specific CD8+T cells are associated with viral control, while CD8+T cells specific for envelope and polymerase epitopes can occasionally be found in the setting of high levels (>107copies) of HBV replication. These findings have implications for the design of immunotherapy for chronic HBV infections.
Styrylquinolines, Integrase Inhibitors Acting Prior to Integration: a New Mechanism of Action for Anti-Integrase Agents
Authors: Bonnenfant Sabine , Thomas Claire Marie , Vita Claudio , Subra Frédéric , Deprez Eric , Zouhiri Fatima , Desmaële Didier , d'Angelo Jean , Mouscadet Jean François , Leh Hervé 
Published: May 2004

ABSTRACT
We have previously shown that styrylquinolines (SQLs) are integrase inhibitors in vitro. They compete with the long terminal repeat substrate for integrase. Here, we describe the cellular mode of action of these molecules. We show that SQLs do not interfere with virus entry. In fact, concentrations of up to 20 times the 50% inhibitory concentration did not inhibit cell-to-cell fusion or affect the interaction between GP120 and CD4 in vitro. Moreover, the pseudotype of the retrovirus envelope did not affect drug activity. Quantitative reverse transcription PCR experiments showed that SQLs do not inhibit the entry of the genomic RNA. In contrast, the treatment of human immunodeficiency virus type 1-infected cells with SQLs reduced the amount of the late cDNA, suggesting for the first time that integrase targeting molecules may affect the accumulation of DNA during reverse transcription. The cellular target of SQLs was confirmed by the appearance of mutations in the integrase gene when viruses were grown in the presence of increasing concentrations of SQLs. Finally, these mutations led to SQL-resistant viruses when introduced into the wild-type sequence. In contrast, SQLs were fully active against reverse transcriptase inhibitor- and diketo acid-resistant viruses, positioning SQLs as a second group of anti-integrase compounds.
Disruption of the Actin Cytoskeleton Can Complement the Ability of Nef To Enhance Human Immunodeficiency Virus Type 1 Infectivity
Authors: Campbell Edward M. , Nunez Rafael , Hope Thomas J. 
Published: May 2004

ABSTRACT
The human immunodeficiency virus (HIV) protein Nef has been shown to increase the infectivity of HIV at an early point during infection. Since Nef is known to interact with proteins involved in actin cytoskeleton rearrangements, we tested the possibility that Nef may enhance HIV infectivity via a mechanism that involves the actin cytoskeleton. We find that disruption of the actin cytoskeleton complements the Nef infectivity defect. The ability of disruption of the actin cytoskeleton to complement the Nef defect was specific to envelopes that fuse at the cell surface, including a variety of HIV envelopes and the murine leukemia virus amphotropic envelope. In contrast, the infectivity of HIV virions pseudotyped to enter cells via endocytosis, which is known to complement the HIV Nef infectivity defect and can naturally penetrate the cortical actin barrier, was not altered by actin cytoskeleton disruption. The results presented here suggest that Nef functions to allow the HIV genome to penetrate the cortical actin network, a known barrier for intracellular parasitic organisms.
Reduced Sensitivity to Human Serum Inactivation of Enveloped Viruses Produced by Pig Cells Transgenic for Human CD55 or Deficient for the Galactosyl-α(1-3) Galactosyl Epitope
Authors: Magre Saema , Takeuchi Yasuhiro , Langford Gillian , Richards Andrew , Patience Clive , Weiss Robin 
Published: May 2004

ABSTRACTComplement activation mediated by the major xenogeneic epitope in the pig, galactosyl-α(1-3) galactosyl sugar structure (α-Gal), and human natural antibodies could cause hyperacute rejection (HAR) in pig-to-human xenotransplantation. The same reaction on viruses bearing α-Gal may serve as a barrier to zoonotic infection. Expressing human complement regulatory proteins or knocking out α-Gal epitopes in pig in order to overcome HAR may therefore pose an increased risk in xenotransplantation with regard to zoonosis. We investigated whether amphotropic murine leukemia virus, porcine endogenous retrovirus, and vesicular stomatitis virus (VSV) budding from primary transgenic pig aortic endothelial (TgPAE) cells expressing human CD55 (hCD55 or hDAF) was protected from human-complement-mediated inactivation. VSV propagated through the ST-IOWA pig cell line, in which α-galactosyl-transferase genes were disrupted (Gal null), was also tested for sensitivity to human complement. The TgPAE cells were positive for hCD55, and all pig cells except the Gal-null ST-IOWA expressed α-Gal epitopes. Through antibody binding, we were able to demonstrate the incorporation of hCD55 onto VSV particles. Viruses harvested from TgPAE cells were relatively resistant to complement-mediated inactivation by the three sources of human sera tested. Additionally, VSV from Gal-null pig cells was resistant to human complement inactivation. Such protection of enveloped viruses may increase the risk of zoonosis from pigs genetically modified for pig-to-human xenotransplantation.
Microarray Analysis Reveals Characteristic Changes of Host Cell Gene Expression in Response to Attenuated Modified Vaccinia Virus Ankara Infection of Human HeLa Cells
Authors: Guerra Susana , López-Fernández Luis A. , Conde Raquel , Pascual-Montano Alberto , Harshman Keith , Esteban Mariano 
Published: May 2004

ABSTRACT
The potential use of the modified vaccinia virus Ankara (MVA) strain as a live recombinant vector to deliver antigens and elicit protective immune responses against infectious diseases demands a comprehensive understanding of the effect of MVA infection on human host gene expression. We used microarrays containing more than 15,000 human cDNAs to identify gene expression changes in human HeLa cell cultures at 2, 6, and 16 h postinfection. Clustering of the 410 differentially regulated genes identified 11 discrete gene clusters with altered expression patterns after MVA infection. Clusters 1 and 2 (accounting for 16.59% [68 of 410] of the genes) contained 68 transcripts showing a robust induction pattern that was maintained during the course of infection. Changes in cellular gene transcription detected by microarrays after MVA infection were confirmed for selected genes by Northern blot analysis and by real-time reverse transcription-PCR. Upregulated transcripts in clusters 1 and 2 included 20 genes implicated in immune responses, including interleukin 1A (IL-1A), IL-6, IL-7, IL-8, and IL-15 genes. MVA infection also stimulated the expression of NF-κB and components of the NF-κB signal transduction pathway, including p50 and TRAF-interacting protein. A marked increase in the expression of histone family members was also induced during MVA infection. Expression of the Wiskott-Aldrich syndrome family members WAS, WASF1, and the small GTP-binding protein RAC-1, which are involved in actin cytoskeleton reorganization, was enhanced after MVA infection. This study demonstrates that MVA infection triggered the induction of groups of genes, some of which may be involved in host resistance and immune modulation during virus infection.
Human Immunodeficiency Virus Type 1 (HIV-1) Integrase: Resistance to Diketo Acid Integrase Inhibitors Impairs HIV-1 Replication and Integration and Confers Cross-Resistance to
l
-Chicoric Acid
Authors: Lee Deborah J. , Robinson W. E. 
Published: May 2004

ABSTRACT

The diketo acids are potent inhibitors of human immunodeficiency virus (HIV) integrase (IN). Mutations in IN, T66I, S153Y, and M154I, as well as T66I-S153Y and T66I-M154I double mutations, confer resistance to diketo acids (D. J. Hazuda et al., Science
287:
646-650, 2000). The effects of these IN mutations on viral replication, enzymatic activity, and susceptibility to other HIV inhibitors are reported herein. By immunofluorescence assay and real-time PCR, all mutant viruses demonstrated a modest delay in viral spread compared to that of reference HIV. These viruses also showed a statistically significant defect in integration without defects in reverse transcription. Recombinant IN containing S153Y, T66I, and M154I-T66I mutations had an approximately twofold decrease in both disintegration and 3′-end-processing-strand transfer activities in vitro. In contrast, IN containing M154I demonstrated a greater than twofold increase in specific activity in both reactions. All mutant HIVs were resistant to
l
-chicoric acid, a dicaffeoyltartaric acid IN inhibitor, both in tissue culture and in biochemical assays, yet remained susceptible to the reverse transcriptase inhibitors zidovudine and nevirapine. Thus, IN mutations conferring resistance to the diketo acids can yield integration defects, attenuated catalysis in vitro, and cross-resistance to
l
-chicoric acid.
Integrase-Specific Enhancement and Suppression of Retroviral DNA Integration by Compacted Chromatin Structure In Vitro
Authors: Taganov Konstantin D. , Cuesta Isabel , Daniel René , Cirillo Lisa Ann , Katz Richard A. , Zaret Kenneth S. , Skalka Anna Marie 
Published: May 2004

ABSTRACT
Integration of viral DNA into the host chromosome is an obligatory step in retroviral replication and is dependent on the activity of the viral enzyme integrase. To examine the influence of chromatin structure on retroviral DNA integration in vitro, we used a model target comprising a 13-nucleosome extended array that includes binding sites for specific transcription factors and can be compacted into a higher-ordered structure. We found that the efficiency of in vitro integration catalyzed by human immunodeficiency virus type 1 (HIV-1) integrase was decreased after compaction of this target with histone H1. In contrast, integration by avian sarcoma virus (ASV) integrase was more efficient after compaction by either histone H1 or a high salt concentration, suggesting that the compacted structure enhances this reaction. Furthermore, although site-specific binding of transcription factors HNF3 and GATA4 blocked ASV DNA integration in extended nucleosome arrays, local opening of H1-compacted chromatin by HNF3 had no detectable effect on integration, underscoring the preference of ASV for compacted chromatin. Our results indicate that chromatin structure affects integration site selection of the HIV-1 and ASV integrases in opposite ways. These distinct properties of integrases may also affect target site selection in vivo, resulting in an important bias against or in favor of integration into actively transcribed host DNA.
The NV Gene of Snakehead Rhabdovirus (SHRV) Is Not Required for Pathogenesis, and a Heterologous Glycoprotein Can Be Incorporated into the SHRV Envelope
Authors: Alonso Marta , Kim Carol H. , Johnson Marc C. , Pressley Meagan , Leong Jo-Ann 
Published: May 2004

ABSTRACT

Snakehead rhabdovirus
(SHRV) affects warm-water fish in Southeast Asia and belongs to the genus
Novirhabdovirus
by virtue of its “nonvirion” (NV) gene. To examine the function of the NV gene, we used a recently developed reverse genetic system to produce a viable recombinant SHRV carrying an NV gene deletion. The recombinant virus was produced at the same rate and same final concentrations as the wild-type virus in cultured fish cells in spite of the NV gene deletion. The role of the NV protein in fish pathogenesis was also investigated. Zebra fish (
Danio rerio
) were infected with the NV deletion mutant or with a recombinant virus containing a copy of the SHRV genome, and similar mortality rates as well as final mortalities were recorded, suggesting no apparent role for the NV protein in fish pathogenesis. Interestingly, the unsuccessful rescue of fully viable recombinants with genomes containing deletions in the G/NV gene junction suggested a role for the gene junction in virus transcription and replication. Finally, we demonstrated that the SHRV glycoprotein can be replaced by the glycoprotein of infectious hematopoietic necrosis virus (IHNV) or by a hybrid protein composed of SHRV and IHNV sequences.