bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Latency-Associated Nuclear Antigen of Kaposi's Sarcoma-Associated Herpesvirus Manipulates the Activity of Glycogen Synthase Kinase-3β
Authors: Fujimuro Masahiro , Hayward S. Diane 
Published: June 2003

ABSTRACT
The latency-associated nuclear antigen (LANA) of Kaposi's sarcoma-associated herpesvirus (KSHV) is expressed in all KSHV-associated malignancies. LANA is essential for replication and maintenance of the viral episomes during latent infection. However, LANA also has a transcriptional regulatory role and can affect gene expression both positively and negatively. A previously performed yeast two-hybrid screen identified glycogen synthase kinase 3 (GSK-3) as a LANA-interacting protein. Interaction with both GSK-3α and GSK-3β was confirmed in transfected cells with coprecipitation assays. GSK-3β also interacted with the herpesvirus saimiri homolog ORF73. GSK-3β is an intermediate in the Wnt signaling pathway and a negative regulator of β-catenin. In transfected cells, LANA was shown to overcome GSK-3β-mediated degradation of β-catenin. Examination of primary effusion lymphoma (PEL) cells found increased levels of β-catenin relative to KSHV-negative B cells, and this translated into increased activity of a β-catenin-responsive reporter containing Tcf/Lef binding sites. In tetradecanoyl phorbol acetate-treated PEL cells, loss of LANA expression correlated temporally with loss of detectable β-catenin. LANA was found to alter the intracellular distribution of GSK-3β so that nuclear GSK-3β was more readily detectable in the presence of LANA. Mapping experiments with coimmunoprecipitation assays revealed that both N-terminal and C-terminal LANA sequences were required for efficient GSK-3β interaction. LANA mutants that were defective for GSK-3β interaction were unable to mediate GSK-3β relocalization or activate a β-catenin-responsive Tcf-luciferase reporter. This study identified manipulation of GSK-3β activity as a mechanism by which LANA may modify transcriptional activity and contribute to the phenotype of primary effusion lymphoma.
Vesicular Stomatitis Virus Glycoprotein Is a Determinant of Pathogenesis in Swine, a Natural Host
Authors: Martinez Isidoro , Rodriguez Luis L. , Jimenez Carlos , Pauszek Steven J. , Wertz Gail W. 
Published: June 2003

ABSTRACT

There are two major serotypes of vesicular stomatitis virus (VSV), Indiana (VSIV) and New Jersey (VSNJV). We recovered recombinant VSIVs from engineered cDNAs that contained either (i) one copy of the VSIV G gene (VSIV-G
I
); (ii) two copies of the G gene, one from each serotype (VSIV-G
NJ
G
I
); or (iii) a single copy of the G
NJ
gene instead of the G
I
gene (VSIV-G
NJ
). The recombinant viruses expressed the appropriate glycoproteins, incorporated them into virions, and were neutralized by antibodies specific for VSIV (VSIV-G
I
), VSNJV (VSIV-G
NJ
), or both (VSIV-G
NJ
G
I
), according to the glycoprotein(s) they expressed. All recombinant viruses grew to similar titers in cell culture. In mice, VSIV-G
NJ
and VSIV-G
NJ
G
I
were attenuated. However, in swine, a natural host for VSV, the G
NJ
glycoprotein-containing viruses caused more severe lesions and replicated to higher titers than the parental virus, VSIV-G
I
. These observations implicate the glycoprotein as a determinant of VSV virulence in a natural host and emphasize the differences in VSV pathogenesis between mice and swine.
Novel PKCηIs Required To Activate Replicative Functions of the Major Nonstructural Protein NS1 of Minute Virus of Mice
Authors: Lachmann Sylvie , Rommeleare Jean , Nüesch Jürg P. F. 
Published: June 2003

ABSTRACTThe multifunctional protein NS1 of minute virus of mice (MVMp) is posttranslationally modified and at least in part regulated by phosphorylation. The atypical lambda isoform of protein kinase C (PKCλ) phosphorylates residues T435 and S473 in vitro and in vivo, leading directly to an activation of NS1 helicase function, but it is insufficient to activate NS1 for rolling circle replication. The present study identifies an additional cellular protein kinase phosphorylating and regulating NS1 activities. We show in vitro that the recombinant novel PKCη phosphorylates NS1 and in consequence is able to activate the viral polypeptide in concert with PKCλ for rolling circle replication. Moreover, this role of PKCη was confirmed in vivo. We thereby created stably transfected A9 mouse fibroblasts, a typical MVMp-permissive host cell line with Flag-tagged constitutively active or inactive PKCη mutants, in order to alter the activity of the NS1 regulating kinase. Indeed, tryptic phosphopeptide analyses of metabolically32P-labeled NS1 expressed in the presence of a dominant-negative mutant, PKCηDN, showed a lack of distinct NS1 phosphorylation events. This correlates with impaired synthesis of viral DNA replication intermediates, as detected by Southern blotting at the level of the whole cell population and by BrdU incorporation at the single-cell level. Remarkably, MVM infection triggers an accumulation of endogenous PKCηin the nuclear periphery, suggesting that besides being a target for PKCη, parvovirus infections may also affect the regulation of this NS1 regulating kinase. Altogether, our results underline the tight interconnection between PKC-mediated signaling and the parvoviral life cycle.
Multiple Interactions across the Surface of the gp120 Core Structure Determine the Global Neutralization Resistance Phenotype of Human Immunodeficiency Virus Type 1
Authors: Bouma Peter , Leavitt Maria , Zhang Peng Fei , Sidorov Igor A. , Dimitrov Dimiter S. , Quinnan Gerald V. 
Published: June 2003

ABSTRACT
Resistance to neutralization is an important characteristic of primary isolates of human immunodeficiency virus type 1 (HIV-1) that relates to the potential for successful vaccination to prevent infection and use of immunotherapeutics for treatment of established infection. In order to further elucidate mechanisms responsible for neutralization resistance, we studied the molecular mechanisms that determine the resistance of the primary virus isolate of the strain HIV-1 MN to neutralization by soluble CD4 (sCD4). As is the case for the global neutralization resistance phenotype, sCD4 resistance depended upon sequences in the amino-terminal heptad repeat region of gp41 (HR1), as well as on multiple functional interactions within the envelope complex. The functional interactions that determined the resistance included interactions between the variable loop 1 and 2 (V1/V2) region and sequences in or near the CD4 binding site (CD4bs) and with the V3 loop. Additionally, the V3 loop region was found to interact functionally with sequences in the outer domain of gp120, distant from the CD4bs and coreceptor-binding site, as well as with a residue thought to be located centrally in the coreceptor-binding site. These and previous results provide the basis for a model by which functional signals that determine the neutralization resistance, high-infectivity phenotype depend upon interactions occurring across the surface of the gp120 core structure and involving variable loop structures and gp41. This model should be useful in efforts to define epitopes that may be important for primary virus neutralization.
Structural Analysis of the Kaposi's Sarcoma-Associated Herpesvirus K1 Protein
Authors: Lee Bok-Soo , Connole Michelle , Tang Zuoquin , Harris Nancy L. , Jung Jae U. 
Published: June 2003

ABSTRACT
The K1 protein of Kaposi's sarcoma-associated herpesvirus (KSHV) efficiently transduces extracellular signals to elicit cellular activation events through its cytoplasmic immunoreceptor tyrosine-based activation motif (ITAM). In addition, the extracellular domain of K1 demonstrates regional homology with the immunoglobulin (Ig) family and contains conserved regions (C1 and C2) and variable regions (V1 and V2). To generate mouse monoclonal antibodies directed against the KSHV K1 protein, BALB/c mice were primed and given boosters with K1 protein purified from mammalian cells. Twenty-eight hybridomas were tested for reactivity with K1 protein by enzyme-linked immunosorbent assay, immunofluorescence, flow cytometry, immunohistochemistry, and immunoblotting. Deletion mutants of the K1 extracellular domain were used to map the epitope of each antibody. All antibodies were directed to the Ig, C1, and C2 regions of K1. Furthermore, antibody recognition of a short sequence (amino acids 92 to 125) of the C2 region overlapping with the Ig region of K1 efficiently induced intracellular free calcium mobilization; antibody recognition of the other regions of K1 did not. The efficient signal transduction of K1 induced by antibody stimulation required both the ITAM sequence of the cytoplasmic domain and the normal structure of the extracellular domain. Finally, immunological assays showed that K1 was expressed during the early lytic cycle of viral replication in primary effusion lymphoma cells. K1 was readily detected in multicentric Castleman's disease tissues, whereas it was not detected in Kaposi's sarcoma lesions, suggesting that K1 is preferentially expressed in lymphoid cells. Thus, these results indicate that the conserved regions, particularly the Ig and C2 regions, of the K1 extracellular domain are exposed on the outer surface and play an important role in K1 structure and signal transduction, whereas the variable regions of K1 appear to be away from the surface.
An Activity Associated with Human Chromosome 21 Permits Nuclear Colocalization of the Adenovirus E1B-55K and E4orf6 Proteins and Promotes Viral Late Gene Expression
Authors: Chastain-Moore Amy M. , Roberts Terry , Trott Deborah A. , Newbold Robert F. , Ornelles David A. 
Published: June 2003

ABSTRACT
The adenovirus E1B-55K and E4orf6 proteins cooperate during virus infection while performing several tasks that contribute to a productive infection, including the selective nucleocytoplasmic transport of late viral mRNA. Previous studies have shown that the E4orf6 protein retains the E1B-55K protein in the nucleus of human and monkey cells, but not in those of rodents, suggesting that primate-specific cellular factors contribute to the E4orf6-mediated retention of the E1B-55K protein in the nucleus. In an effort to identify these proposed primate-specific cellular factors, the interaction of the E1B-55K and E4orf6 proteins was studied in a panel of stable human-rodent monochromosomal somatic cell hybrids. Analysis of this panel of cell lines has demonstrated the existence of an activity associated with human chromosome 21 that permits the E1B-55K and E4orf6 proteins to colocalize in the nucleus of a rodent cell. Additional hybrid cells bearing portions of human chromosome 21 were used to map this activity to a 10-megabase-pair segment of the chromosome, extending from 21q22.12 to a region near the q terminus. Strikingly, this region also facilitates the expression of adenovirus late genes in a rodent cell background while having little impact on the expression of early viral genes.
Human Herpesvirus 7 Open Reading Frame U12 Encodes a Functional β-Chemokine Receptor
Authors: Nakano Kazushi , Tadagaki Kenjiro , Isegawa Yuji , Aye Mya Mya , Zou Ping , Yamanishi Koichi 
Published: June 2003

ABSTRACTHuman herpesvirus 7 (HHV-7), which belongs to the betaherpesvirus subfamily, infects mainly CD4+T cells in vitro and infects children during infancy. After the primary infection, HHV-7 becomes latent. HHV-7 contains two genes (U12 and U51) that encode putative homologs of cellular G-protein-coupled receptors. To analyze the biological function of the U12 gene, we cloned the gene and expressed the U12 protein in cells. The U12 gene encoded a calcium-mobilizing receptor for the EBI1 ligand chemokine-macrophage inflammatory protein 3β (ELC/MIP-3β) but not for other chemokines, suggesting that the chemokine selectivity of the U12 gene product is distinct from that of the known mammalian chemokine receptors. These studies revealed that U12 activates distinct transmembrane signaling pathways that may mediate biological functions by binding with a β-chemokine, ELC/MIP-3β.
Cooperative Interactions of Simian Immunodeficiency Virus Nef, AP-2, and CD3-ζ Mediate the Selective Induction of T-Cell Receptor-CD3 Endocytosis
Authors: Swigut Tomek , Greenberg Michael , Skowronski Jacek 
Published: June 2003

ABSTRACTThe Nef proteins of human immunodeficiency virus and simian immunodeficiency virus (SIV) bind the AP-1 and AP-2 clathrin adaptors to downmodulate the expression of CD4 and CD28 by recruiting them to sites of AP-2 clathrin-dependent endocytosis. Additionally, SIV Nef directly binds the CD3-ζ subunit of the CD3 complex and downmodulates the T-cell receptor (TCR)-CD3 complex. We report here that SIV mac239 Nef induces the endocytosis of TCR-CD3 in Jurkat T cells. SIV Nef also induces the endocytosis of a chimeric CD8-CD3-ζ protein containing only the CD3-ζ cytoplasmic domain (8-ζ), in the absence of other CD3 subunits. Thus, the interaction of SIV Nef with CD3-ζ likely mediates the induction of TCR-CD3 endocytosis. In cells expressing SIV Nef and 8-ζ, both proteins colocalize with AP-2, indicating that Nef induces 8-ζ internalization via this pathway. Surprisingly, deletion of constitutively strong AP-2 binding determinants (CAIDs) in SIV Nef had little effect on its ability to induce TCR-CD3, or 8-ζ endocytosis, even though these determinants are required for the induction of CD4 and CD28 endocytosis via this pathway. Fluorescent microscopic analyses revealed that while neither the mutant SIV Nef protein nor 8-ζ colocalized with AP-2 when expressed independently, both proteins colocalized with AP-2 when coexpressed. In vitro binding studies using recombinant SIV Nef proteins lacking CAIDs and recombinant CD3-ζ cytoplasmic domain demonstrated that SIV Nef and CD3-ζ cooperate to bind AP-2 via a novel interaction. The fact that Nef uses distinct AP-2 interaction surfaces to recruit specific membrane receptors demonstrates how Nef independently selects distinct types of target receptors and recruits them to AP-2 for endocytosis.
Biphasic DNA Synthesis in Spumaviruses
Authors: Delelis Olivier , Saïb Ali , Sonigo Pierre 
Published: June 2003

ABSTRACT
Spumaviruses are complex retroviruses whose replication cycle resembles that of hepadnaviruses, especially by a late-occurring reverse transcription step. The possible existence of an early reverse transcription as observed in other retroviruses was not documented. Using real-time quantitative PCR, we addressed directly the kinetics of DNA synthesis during spumavirus infection. An early phase of viral DNA synthesis developed until 3 h postinfection, followed by a second phase, culminating 10 h postinfection. Both phases were abolished by the reverse transcriptase inhibitor 3′-azido-3′-deoxythymidine. Similar to other retroviruses, circular forms of viral DNA harboring two long terminal repeats were mainly found in the nucleus of infected cells. Interestingly, a fraction of these circular forms were detected in the cytoplasm and in extracellular virions, a feature shared with hepadnaviruses. Combined with packaging of both viral DNA and RNA genomes in virions, early and late reverse transcription might allow spumavirus to maximize its genome replication.
Characterization of Entry Mechanisms of Human Herpesvirus 8 by Using an Rta-Dependent Reporter Cell Line
Authors: Inoue Naoki , Winter Jörn , Lal Renu B. , Offermann Margaret K. , Koyano Shin 
Published: June 2003

ABSTRACT

To analyze the mechanisms of entry of human herpesvirus 8 (HHV-8), we established a reporter cell line T1H6 that contains the
lac
Z gene under the control of the polyadenylated nuclear RNA promoter, known to be strongly activated by a viral transactivator, Rta. We found that infection with cell-free virus, as well as cocultivation with HHV-8-positive primary effusion lymphoma cell lines, activated the
lac
Z gene of T1H6 in a sensitive and dose-dependent manner. Addition of Polybrene and centrifugation enhanced, but polysulfonate compounds inhibited, the HHV-8 infectivity. RGD-motif-containing polypeptides and integrins did not decrease the infectivity, suggesting the presence of an additional cellular receptor other than the reported one. The entry was dependent on pH acidification but not on the clathrin pathway. Although conditioned media obtained from human immunodeficiency virus (HIV)-infected cells did not have any effect on the early steps of HHV-8 infection, intracellular expression of a proviral HIV type 1, but not of Tat alone, increased the HHV-8-dependent reporter activation slightly, suggesting a potential of HIV-mediated enhancement of an early step of HHV-8 infection.
Identification and Simian Immunodeficiency Virus Infection of CD1d-Restricted Macaque Natural Killer T Cells
Authors: Motsinger Alison , Azimzadeh Agnes , Stanic Aleksandar K. , Johnson R. Paul , Van Kaer Luc , Joyce Sebastian , Unutmaz Derya 
Published: June 2003

ABSTRACTNatural killer T (NKT) cells express a highly conserved T-cell receptor (TCR) and recognize glycolipids in the context of CD1d molecules. We recently demonstrated that CD4+NKT cells are highly susceptible to human immunodeficiency virus type 1 (HIV-1) infection and are selectively depleted in HIV-infected individuals. Here, we identified macaque NKT cells using CD1d tetramers and human Vα24 antibodies. Similar to human NKT cells, α-galactosylceramide (α-GalCer)-pulsed dendritic cells activate and expand macaque NKT cells. Upon restimulation with α-GalCer-pulsed CD1d+cells, macaque NKT cells secreted high levels of cytokines, a characteristic of these T cells. Remarkably, the majority of resting and activated macaque NKT cells expressed CD8, and a smaller portion expressed CD4. Macaque NKT cells also expressed the HIV-1/simian immunodeficiency virus (SIV) coreceptor CCR5, and the CD4+subset was susceptible to SIV infection. Identification of macaque NKT cells has major implications for delineating the role of these cells in nonhuman primate disease models of HIV as well as other pathological conditions, such as allograft rejection and autoimmunity.
Novel Kaposi's Sarcoma-Associated Herpesvirus Homolog in Baboons
Authors: Whitby Denise , Stossel Andrea , Gamache Christine , Papin James , Bosch Marnix , Smith Anne , Kedes Dean H. , White Gary , Kennedy Ronald , Dittmer Dirk P. 
Published: June 2003

ABSTRACTKaposi's sarcoma (KS) and lymphoproliferative diseases induced by KS-associated herpesvirus (KSHV/human herpesvirus 8) cause substantial morbidity and mortality in human immunodeficiency virus-infected individuals. To understand KSHV biology it is useful to investigate closely related rhadinoviruses naturally occurring in nonhuman primates. Here we report evidence for a novel KSHV homolog in captive baboon species (Papio anubisand other). Using degenerate PCR we identified a novel rhadinovirus, PapRV2, that has substantial sequence identity to two essential KSHV genes, the viral polymerase and thymidylate synthase. A subset of animals exhibited detectable PapRV2 viral load in peripheral blood mononuclear cells. Extensive serological analysis of nearly 200 animals in the colony demonstrated that the majority carried cross-reacting antibodies that recognize KSHV or macaque rhadinovirus antigens. Seroreactivity increased with age, similar to the age-specific prevalence of KSHV in the human population. This establishes baboons as a novel resource to investigate rhadinovirus biology, which can be developed into an animal model system for KSHV-associated human diseases, vaccine development, and therapy evaluation.
Differential Hyperacetylation of Histones H3 and H4 upon Promoter-Specific Recruitment of EBNA2 in Epstein-Barr Virus Chromatin
Authors: Alazard Nathalie , Gruffat Henri , Hiriart Edwige , Sergeant Alain , Manet Evelyne 
Published: June 2003

ABSTRACT
Epstein-Barr virus nuclear antigen 2 (EBNA2) is a transcriptional activator involved in the immortalization of B lymphocytes by the virus. EBNA2 is targeted to the promoters of its responsive genes, via interaction with cellular DNA-binding proteins. Using chromatin immunoprecipitation assays, we show for the first time the conditional recruitment of EBNA2 on two specific viral promoters in vivo and demonstrate a correlation between this recruitment and a local change in the acetylation of histones H3 and H4, which is promoter dependent.
ON EFFICIENT METHODS FOR DETECTING HOPF BIFURCATION WITH APPLICATIONS TO POWER SYSTEM INSTABILITY PREDICTION
Authors: HUSSEIN A. , CHEN K. 
Published: June 2003

Efficient measurement of the performance index (the distance of a loading parameter from the voltage collapse or instability point) is one of the key problems in power system operations and planning such an index indicates the severity of a power system with regard to voltage collapse or instability. While much work has been done on the former problem, the latter problem poses a more severe challenge both to the engineering and mathematical communities. This paper first presents a review of the main methods for detecting Hopf bifurcation in the general field of bifurcation theory and then attempts to generalize the previously studied fold detection and index methods to the Hopf case. The proposed Hopf test functions should be of wide interest while the proposed test function based index method gives an indication of the distance of the current operating point from the Hopf instability. Promising numerical results have been obtained using some standard dynamical test systems.
Rosuvastatin – A Highly Effective New 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Inhibitor: Review of Clinical Trial Data at 10–40 mg Doses in Dyslipidemic Patients
Authors: Schuster Herbert 
Published: June 2003

Rosuvastatin (Crestor<sup>®</sup>; licensed to AstraZeneca, Macclesfield, UK from Shionogi, Osaka, Japan) is a new statin with pharmacologic characteristics that translate into selectivity of effect in hepatic cells and enhanced potency in 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibition. It is approved for use at doses of 10–40 mg once daily to reduce low-density lipoprotein (LDL) cholesterol, increase high-density lipoprotein (HDL) cholesterol and improve other lipid measures in dyslipidemic patients. In a dose-ranging study in mild/moderate hypercholesterolemia, rosuvastatin reduced LDL cholesterol by 52–63% at 10–40 mg. Rosuvastatin 10 mg reduces LDL cholesterol significantly more than atorvastatin 10 mg, simvastatin 10–40 mg and pravastatin 10–40 mg, and enables significantly more patients to achieve National Cholesterol Education Program and Joint European Societies LDL cholesterol goals compared with each of these statins. Rosuvastatin also produces marked elevations in HDL cholesterol and maintains this effect across the dose range. Rosuvastatin favorably modifies triglycerides, LDL cholesterol and other lipid measures in patients with hypertriglyceridemia or mixed dyslipidemia, including diabetic patients, and may constitute a monotherapy option for many such patients. Rosuvastatin is well tolerated when used alone or in combination, exhibiting a safety profile similar to that of other available statins. Rosuvastatin offers considerable advantages for use in routine clinical practice.