bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modulation of Different Human Immunodeficiency Virus Type 1 Nef Functions during Progression to AIDS
Authors: Carl Silke , Greenough Thomas C. , Krumbiegel Mandy , Greenberg Michael , Skowronski Jacek , Sullivan John L. , Kirchhoff Frank 
Published: July 2002

ABSTRACT

The human immunodeficiency virus type 1 (HIV-1) Nef protein has several independent functions that might contribute to efficient viral replication in vivo. Since HIV-1 adapts rapidly to its host environment, we investigated if different Nef properties are associated with disease progression. Functional analysis revealed that
nef
alleles obtained during late stages of infection did not efficiently downmodulate class I major histocompatibility complex but were highly active in the stimulation of viral replication. In comparison, functional activity in downregulation of CD4 and enhancement of HIV-1 infectivity were maintained or enhanced after AIDS progression. Our results demonstrate that various Nef activities are modulated during the course of HIV-1 infection to maintain high viral loads at different stages of disease progression. These findings suggest that all in vitro Nef functions investigated contribute to AIDS pathogenesis and indicate that
nef
variants with increased pathogenicity emerge in a significant number of HIV-1-infected individuals.
Ability of the V3 Loop of Simian Immunodeficiency Virus To Serve as a Target for Antibody-Mediated Neutralization: Correlation of Neutralization Sensitivity, Growth in Macrophages, and Decreased Dependence on CD4
Authors: Means Robert E. , Matthews Thomas , Hoxie James A. , Malim Michael H. , Kodama Toshiaki , Desrosiers Ronald C. 
Published: July 2002

ABSTRACT

To better define the effects of sequence variation and tropism on the ability of the simian immunodeficiency virus SIVmac V3 loop to act as a target of antibody-mediated neutralization, a series of experiments were performed. Three SIV strains, SIVmac239, SIVmac316, and SIVmac155/T3, each with defined differences in
env
sequence and tropism, were used to construct a panel of viruses chimeric for a portion of envelope that includes the V2 and V3 regions. Peptides with sequences corresponding to the V3 loops of the parental viruses were used to immunize rabbits. The polyclonal rabbit antibodies and plasma from SIVmac239-infected animals were then used to assess the neutralization sensitivity of the parental and chimeric viruses. One of the parental viruses, SIVmac316, which is able to replicate to high titer in alveolar macrophages and can infect cells in a CD4-independent fashion, was highly sensitive to neutralization by plasma from SIVmac-infected rhesus macaques, with average 50% neutralization titers of 1:20,480; this same strain was also sensitive to neutralization by the anti-V3 loop peptide sera. Other parental and chimeric viruses were less sensitive to neutralization with this same panel of antibodies, but as seen with SIVmac316, those viruses that were able to productively replicate in alveolar macrophages were more sensitive to antibody-mediated neutralization. To further define the amino acids involved in increased sensitivity to neutralization, a panel of viruses was constructed by changing envelope residues in SIVmac316 to the corresponding SIVmac239 amino acids. The increased neutralization sensitivity observed for SIVmac316 was mapped principally to three amino acid changes spread throughout gp120. In addition, the increased sensitivity to neutralization by V3-directed antibodies correlated with the ability of the various viruses to replicate to high levels in alveolar macrophage cultures and a CD4-negative cell line, BC7/CCR5. These results demonstrate that the V3 loop of SIVmac Env can act as an efficient target of neutralizing antibodies in a fashion that is highly dependent on sequence context. In addition, these studies suggest a correlation between decreased dependence on CD4 and increased sensitivity to antibody-mediated neutralization.
Quintuple Deglycosylation Mutant of Simian Immunodeficiency Virus SIVmac239 in Rhesus Macaques: Robust Primary Replication, Tightly Contained Chronic Infection, and Elicitation of Potent Immunity against the Parental Wild-Type Strain
Authors: Mori Kazuyasu , Yasutomi Yasuhiro , Ohgimoto Shinji , Nakasone Tadashi , Takamura Shiki , Shioda Tatsuo , Nagai Yoshiyuki 
Published: July 2002

ABSTRACT
We previously generated a mutant of simian immunodeficiency virus (SIV) lacking 5 of a total of 22 N-glycans in its external envelope protein gp120 with no impairment in viral replication capability and infectivity in tissue culture cells. Here, we infected rhesus macaques with this mutant and found that it also replicated robustly in the acute phase but was tightly, though not completely, contained in the chronic phase. Thus, a critical requirement for the N-glycans for the full extent of chronic infection was demonstrated. No evidence indicating reversion to a wild type was obtained during the observation period of more than 40 weeks. Monkeys infected with the mutant were found to tolerate a challenge infection with wild-type SIV very well. Analyses of host responses following challenge revealed no neutralizing antibodies against the challenge virus but strong secondary responses of cytotoxic T lymphocytes against multiple antigens, including Gag-Pol, Nef, and Env. Thus, the quintuple deglycosylation mutant appeared to represent a novel class of SIV live attenuated vaccine.
Increased Efficacy of the Immunoglobulin G2a Subclass in Antibody-Mediated Protection against Lactate Dehydrogenase-Elevating Virus-Induced Polioencephalomyelitis Revealed with Switch Mutants
Authors: Markine-Goriaynoff Dominique , Coutelier Jean-Paul 
Published: July 2002

ABSTRACTImmunoglobulin G1 (IgG1), IgG2a, and IgG2b switch variants were derived from an IgG3 monoclonal antibody directed against the VP3 envelope glycoprotein of lactate dehydrogenase-elevating virus (LDV). Among the four antibodies, IgG2a delayed the onset and progression of LDV-induced polioencephalomyelitis more than did the other subclasses. This suggests that the IgG2a predominance observed in many IgG antibody responses elicited by live viruses could, at least under some circumstances, correspond to the selection of the best protection for the infected host.
Gammaherpesvirus Lytic Gene Expression as Characterized by DNA Array
Authors: Ahn Joo Wook , Powell Kenneth L. , Kellam Paul , Alber Dagmar G. 
Published: July 2002

ABSTRACT
Gammaherpesviruses are associated with a number of diseases including lymphomas and other malignancies. Murine gammaherpesvirus 68 (MHV-68) constitutes the most amenable animal model for this family of pathogens. However experimental characterization of gammaherpesvirus gene expression, at either the protein or RNA level, lags behind that of other, better-studied alpha- and beta-herpesviruses. We have developed a cDNA array to globally characterize MHV-68 gene expression profiles, thus providing an experimental supplement to a genome that is chiefly annotated by homology. Viral genes started to be transcribed as early as 3 h postinfection (p.i.), and this was followed by a rapid escalation of gene expression that could be seen at 5 h p.i. Individual genes showed their own transcription profiles, and most genes were still being expressed at 18 h p.i. Open reading frames (ORFs) M3 (chemokine-binding protein), 52, and M9 (capsid protein) were particularly noticeable due to their very high levels of expression. Hierarchical cluster analysis of transcription profiles revealed four main groups of genes and allowed functional predictions to be made by comparing expression profiles of uncharacterized genes to those of genes of known function. Each gene was also categorized according to kinetic class by blocking de novo protein synthesis and viral DNA replication in vitro. One gene, ORF 73, was found to be expressed with α-kinetics, 30 genes were found to be expressed with β-kinetics, and 42 genes were found to be expressed with γ-kinetics. This fundamental characterization furthers the development of this model and provides an experimental basis for continued investigation of gammaherpesvirus pathology.
Deubiquitinating Function of Adenovirus Proteinase
Authors: Balakirev Maxim Y. , Jaquinod Michel , Haas Arthur L. , Chroboczek Jadwiga 
Published: July 2002

ABSTRACT
The invasion strategy of many viruses involves the synthesis of viral gene products that mimic the functions of the cellular proteins and thus interfere with the key cellular processes. Here we show that adenovirus infection is accompanied by an increased ubiquitin-cleaving (deubiquitinating) activity in the host cells. Affinity chromatography on ubiquitin aldehyde (Ubal), which was designed to identify the deubiquitinating proteases, revealed the presence of adenovirus L3 23K proteinase (Avp) in the eluate from adenovirus-infected cells. This proteinase is known to be necessary for the processing of viral precursor proteins during virion maturation. We show here that in vivo Avp deubiquitinates a number of cellular proteins. Analysis of the substrate specificity of Avp in vitro demonstrated that the protein deubiquitination by this enzyme could be as efficient as proteolytic processing of viral proteins. The structural model of the Ubal-Avp interaction revealed some similarity between S1-S4 substrate binding sites of Avp and ubiquitin hydrolases. These results may reflect the acquisition of an advantageous property by adenovirus and may indicate the importance of ubiquitin pathways in viral infection.
The Envelope Glycoprotein of Human Endogenous Retrovirus Type W Uses a Divergent Family of Amino Acid Transporters/Cell Surface Receptors
Authors: Lavillette Dimitri , Marin Mariana , Ruggieri Alessia , Mallet François , Cosset François-Loïc , Kabat David 
Published: July 2002

ABSTRACT
The human endogenous retrovirus type W (HERV-W) family includes proviruses with intact protein-coding regions that appear to be under selection pressure, suggesting that some HERV-W proviruses may remain active in higher primates. The envelope glycoprotein (Env) encoded by HERV-W is highly fusogenic, is naturally expressed in human placental syncytiatrophoblasts, and has been reported to function as a superantigen in lymphocyte cultures. Recent evidence suggested that HERV-W Env can mediate syncytium formation by interacting with the human sodium-dependent neutral amino acid transporter type 2 (hASCT2; gene name, SLC1A5) (J.-L. Blond, D. Lavillette, V. Cheynet, O. Bouton, G. Oriol, S. Chapel-Fernandez, B. Mandrand, F. Mallet, and F.-L. Cosset, J. Virol. 74:3321-3329, 2000) and that it can pseudotype human immunodeficiency virus cores (D. S. An, Y. Xie, and I. S. Y. Chen, J. Virol. 75:3488-3489, 2001). By using cell-cell fusion and pseudotype virion infection assays, we found that HERV-W Env efficiently uses both hASCT2 and the related transporter hASCT1 (gene name, SLC1A4) as receptors. In addition, although HERV-W Env mediates only slight syncytium formation or infection of mouse cells, it utilizes the mouse transporters mASCT1 and mASCT2 when their sites for N-linked glycosylation are eliminated by mutagenesis. Consistent with their role as a battlefield in host-virus coevolution, the viral recognition regions in ASCT1 and ASCT2 of humans and mice are highly divergent compared with other regions of these proteins, and their ratios of nonsynonymous to synonymous nucleotide sequence changes are extremely large. The recognition of ASCT1 and ASCT2 despite this divergence of their sequences strongly suggests that the use of both receptors has been highly advantageous for survival and evolution of the HERV-W family of retroviruses.
Identification of Two Cross-Neutralizing Linear Epitopes within the L1 Major Capsid Protein of Human Papillomaviruses
Authors: Combita Alba-Lucia , Touzé Antoine , Bousarghin Latifa , Christensen Neil D. , Coursaget Pierre 
Published: July 2002

ABSTRACT
The neutralizing activities of polyclonal antibodies and monoclonal antibodies (MAbs) obtained by immunization of mice with L1 virus-like particles (VLPs) were investigated by using pseudovirion infectivity assays for human papillomavirus type 16 (HPV-16), HPV-31, HPV-33, HPV-45, HPV-58, and HPV-59 to obtain a better definition of cross-neutralization between high-risk HPVs. In this study, we confirmed and extended previous studies indicating that most genital HPV genotypes represent separate serotypes, and the results suggest that the classification of serotypes is similar to that of genotypes. In addition, three cross-neutralizing MAbs were identified (HPV-16.J4, HPV-16.I23, and HPV-33.E12). MAb HPV-16.J4 recognized a conserved linear epitope located within the FG loop of the L1 protein, and HPV-16.I23 recognized another located within the DE loop. The results suggested that reactivity of MAb HPV-16.I23 to L1 protein is lost when leucine 152 of the HPV-16 L1 protein is replaced by phenylalanine. This confirmed the existence of linear epitopes within the L1 protein that induce neutralizing antibodies, and this is the first evidence that such linear epitopes induce cross-neutralization. However, the cross-neutralization induced by L1 VLPs represents less than 1% of the neutralizing activity induced by the dominant conformational epitopes, and it is questionable whether this is sufficient to offer cross-protection in vivo.
Cross-Protection against Challenge with Puumala Virus after Immunization with Nucleocapsid Proteins from Different Hantaviruses
Authors: de Carvalho Nicacio Cristina , Gonzalez Della Valle Marcelo , Padula Paula , Björling Ewa , Plyusnin Alexander , Lundkvist Åke 
Published: July 2002

ABSTRACT
Hantaviruses are rodent-borne agents that cause hemorrhagic fever with renal syndrome or hantavirus pulmonary syndrome in humans. The nucleocapsid protein (N) is relatively conserved among hantaviruses and highly immunogenic in both laboratory animals and humans, and it has been shown to induce efficient protective immunity in animal models. To investigate the ability of recombinant N (rN) from different hantaviruses to elicit cross-protection, we immunized bank voles with rN from Puumala (PUUV), Topografov (TOPV), Andes (ANDV), and Dobrava (DOBV) viruses and subsequently challenged them with PUUV. All animals immunized with PUUV and TOPV rN were completely protected. In the group immunized with DOBV rN, 7 of 10 animals were protected, while only 3 of 8 animals were protected in the group immunized with ANDV rN, which is more closely related to PUUV rN than DOBV rN. Humoral and cellular immune responses after rN immunization were also investigated. The highest cross-reactive humoral responses against PUUV antigen were detected in sera from ANDV rN-immunized animals, followed by those from TOPV rN-immunized animals, and only very low antibody cross-reactivity was observed in sera from DOBV rN-immunized animals. In proliferation assays, T lymphocytes from animals immunized with all heterologous rNs were as efficiently recalled in vitro by PUUV rN as were T lymphocytes from animals immunized with homologous protein. In summary, this study has shown that hantavirus N can elicit cross-protective immune responses against PUUV, and the results suggest a more important role for the cellular arm of the immune response than for the humoral arm in cross-protection elicited by rN.
Adenovirus Serotype 30 Fiber Does Not Mediate Transduction via the Coxsackie-Adenovirus Receptor
Authors: Law Lane K. , Davidson Beverly L. 
Published: July 2002

ABSTRACT
Prior work by members of our laboratory and others demonstrated that adenovirus serotype 30 (Ad30), a group D adenovirus, exhibited novel transduction characteristics compared to those of serotype 5 (Ad5, belonging to group C). While some serotype D adenoviruses bind to the coxsackie-adenovirus receptor (CAR), the ability of Ad30 fiber to bind CAR is unknown. We amplified and purified Ad30 and cloned the Ad30 fiber by overlap PCR. Alignment of Ad30 fiber with Ad3, Ad35, Ad5, Ad9, and Ad17 revealed that Ad30, like Ad9 and Ad17, has a shortened fiber sequence relative to that of Ad5. The knob region of fiber was 45% identical to that of the Ad5 knob regions. We made a chimeric recombinant virus (Ad5GFPf30) in which the Ad5 fiber (amino acids [aa]47 to 582) was replaced with Ad30 fiber sequences (aa 46 to 372), and CAR-mediated viral entry was determined on CAR-expressing Chinese hamster ovary (CHO) cells. While CAR expression significantly increased Ad5GFP-mediated transduction in CHO cells (from 1 to 36%), it did not enhance Ad5GFPf30 gene transfer. Binding of radiolabeled Ad5GFPf30 or Ad30 wild-type virus was also not improved by the expression of CAR. These results suggest that Ad30 fiber is distinct from Ad5, Ad9, and Ad17 fibers in its inability to direct transduction via CAR.
Human Immunodeficiency Virus Type 1 (HIV-1)Quasispecies at the Sites ofMycobacterium tuberculosisInfectionContribute to Systemic HIV-1 Heterogeneity
Authors: Collins Kalonji R. , Quiñones-Mateu Miguel E. , Wu Mianda , Luzze Henry , Johnson John L. , Hirsch Christina , Toossi Zahra , Arts Eric J. 
Published: July 2002

ABSTRACTWe have recently reported an increased heterogeneity in the human immunodeficiency virus type 1 (HIV-1) envelope gene (env) in HIV-1-infected patients with pulmonary tuberculosis (TB) compared to patients with HIV-1 alone. This increase may be a result of dissemination of lung-derived HIV-1 isolates from sites ofMycobacterium tuberculosisinfection and/or the systemic activation of the immune system in response to TB. To distinguish between these two mechanisms, blood and pleural fluid samples were obtained from HIV-1-infected patients with active pleural TB in Kampala, Uganda (CD4 cell counts of 34 to 705 cells/μl, HIV-1 plasma loads of 2,400 to 280,000 RNA copies/ml, and HIV-1 pleural loads of 7,600 to 4,500,000 RNA copies/ml). The C2-C3 coding region of HIV-1envwas PCR amplified from lysed peripheral blood mononuclear cells and pleural fluid mononuclear cells and reverse transcriptase-PCR amplified from plasma and pleural fluid HIV-1 virions of eight HIV-1 patients with pleural TB. Phylogenetic and phenetic analyses revealed a compartmentalization of HIV-1 quasispecies between blood and pleural space in four of eight patients, with migration events between the compartments. There was a trend for a greater genetic heterogeneity in the pleural space, which may be the result of anM. tuberculosis-mediated increase in HIV-1 replication and/or selection pressure at the site of infection. Collectively, these findings suggest that HIV-1 quasispecies in theM. tuberculosis-infected pleural space may leak into the systemic circulation and lead to increased systemic HIV-1 heterogeneity during TB.
Baculovirus Replication Factor LEF-1 Is a DNA Primase
Authors: Mikhailov Victor S. , Rohrmann George F. 
Published: July 2002

ABSTRACT

The baculovirus replication factors LEF-1 and LEF-2 of the
Autographa californica
multinucleocapsid nucleopolyhedrovirus were overexpressed as fusions containing a hemagglutinin (HA) epitope and a HIS
6
tag using recombinant baculoviruses. LEF-1 was purified to near homogeneity and found to have primase activity in an indirect assay employing
Escherichia coli
DNA polymerase I (Klenow enzyme) and poly(dT) template. The LEF-1 primase products were also directly characterized by electrophoresis in 20% polyacrylamide-8 M urea gels and agarose gels. Primer synthesis was time dependent, and products of several hundred nucleotides or more were observed from the M13 single-stranded DNA (ssDNA) template. The LEF-1 primase was absolutely dependent on divalent cations (Mg
2+
), and optimal activity was supported by 10 mM MgCl
2
. An alkaline pH (8.8 to 9.4) was optimal, whereas monovalent salt (KCl) was inhibitory. Mutation of an invariant aspartic acid in a putative primase domain caused LEF-1 activity to be abolished. Upon ultracentrifugation in glycerol gradients, LEF-1 was found to have a sedimentation coefficient of 3S that is consistent with its being present as a monomer. Elution profiles of LEF-1 and LEF-2 from ssDNA-cellulose and DEAE resin suggested that LEF-2 may bind to both DNA and LEF-1.
Magnitude of Functional CD8+T-Cell Responses to the Gag Protein of Human Immunodeficiency Virus Type 1 Correlates Inversely with Viral Load in Plasma
Authors: Edwards Bradley H. , Bansal Anju , Sabbaj Steffanie , Bakari Janna , Mulligan Mark J. , Goepfert Paul A. 
Published: July 2002

ABSTRACTThe importance of CD8+T-cell responses in the control of human immunodeficiency virus type 1 (HIV-1) infection has been demonstrated, yet few studies have been able to correlate these responses with markers of HIV-1 disease progression. This study measured cell-mediated immune responses using peripheral blood mononuclear cells (PBMC) obtained from 27 patients with chronic HIV-1 infection, the majority of whom were off antiretroviral therapy. The ELISPOT assay was used to detect gamma interferon-secreting PBMC after stimulation with overlapping HIV-1 peptides spanning the Gag, Pol, Env, and Nef proteins in addition to the baculovirus-derived p24 and gp160 proteins. All volunteers had responses to at least one HIV-1-specific peptide. All but one of the subjects (96%) responded to the Gag peptide pool, and 86% responded to the Pol and/or Nef peptide pools. The magnitude and the breadth of T-cell responses directed to either the Gag or p24 peptide pools correlated inversely with viral load in plasma (r= −0.60,P< 0.001 andr= −0.52,P< 0.005, respectively) and directly with absolute CD4+T-cell counts (r= 0.54,P< 0.01 andr= 0.39,P< 0.05, respectively) using the Spearman rank correlation test. Responses to the Pol and integrase peptide pools also correlated with absolute CD4+T-cell counts (r= 0.45,P< 0.05 andr= 0.49,P< 0.01, respectively). No correlation with markers of disease progression was seen with specific T-cell responses directed toward the Env or Nef peptides. These data serve as strong evidence that major histocompatibility complex class I presentation of Gag peptides is an essential feature for any HIV-1 vaccine designed to elicit optimal CD8+T-cell responses.
Nucleoprotein Structure of Immediate-Early Promoters Zp and Rp and of oriLyt of Latent Epstein-Barr Virus Genomes
Authors: Niller Hans Helmut , Salamon Daniel , Uhlig Jörg , Ranf Stefanie , Granz Marcus , Schwarzmann Fritz , Wolf Hans , Minarovits Janos 
Published: July 2002

ABSTRACT
Genomic footprints across Rp, Zp, and oriLyt of Epstein-Barr virus (EBV) have been conducted in a panel of latently infected B-cell lines. Close protein-base contacts were found about 360 nucleotides upstream of the Zp initiation site. Gel shifts and transient transfection assays indicated that an Sp1-NF1 locus may serve as a repressive transcriptional element against Zp induction from latent EBV genomes.
Incidence of injury in amateur rugby league sevens
Authors: Gabbett T J 
Published: July 2002

Objectives: To investigate the incidence, site, and nature of injuries sustained in amateur rugby league sevens tournaments.Methods: A total of 168 players competing in three amateur rugby league sevens tournaments were studied. All injuries sustained during matches were recorded. Information recorded included the name of the injured player and the time, cause, anatomical site, and nature of the injury.Results: The incidence of injury was 283.5 per 1000 playing hours. Some 40% (113.4 per 1000 playing hours) of all injuries sustained were to the lower limb (χ2= 5.3, df = 1, p<0.05). Contusions were the most common type of injury (113.4 per 1000 hours, 40%, χ2= 9.5, df = 4, p<0.05), with most (198.4 per 1000 hours, 70%, χ2= 31.5, df =4, p<0.001) occurring in physical collisions and tackles. An increasing injury incidence was observed over the first (99.2 per 1000 hours), second (198.4 per 1000 hours), third (347.2 per 1000 hours), and fourth (694.4 per 1000 hours) matches played during the tournaments (χ2= 9.2, df = 3, p<0.05).Conclusions: The results of this study suggest that amateur rugby league sevens tournaments, which require players to compete repeatedly on the same day, may hasten the onset of fatigue and predispose to injury.