bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Role of CD8+T Cells and Major Histocompatibility Complex Class I Genes in the Generation of Protective CD4+Th1 Responses during Retrovirus Infection in Mice
Authors: Peterson Karin E. , Stromnes Ingunn , Messer Ron , Hasenkrug Kim , Chesebro Bruce 
Published: July 2002

ABSTRACTCD4+Th1 responses to virus infections are often necessary for the development and maintenance of virus-specific CD8+T-cell responses. However, in the present study with Friend murine retrovirus (FV), the reverse was also found to be true. In the absence of a responderH-2ballele at major histocompatibility complex (MHC) class II loci, a singleH-2DbMHC class I allele was sufficient for the development of a CD4+Th1 response to FV. This effect ofH-2Dbon CD4+T-cell responses was dependent on CD8+T cells, as demonstrated by depletion studies. A direct effect of CD8+T-cell help in the development of CD4+Th1 responses to FV was also shown in vaccine studies. Vaccination of nonresponderH-2a/amice induced FV-specific responses ofH-2Dd-restricted CD8+cytotoxic T lymphocytes (CTL). Adoptive transfer of vaccine-primed CD8+T cells to naiveH-2a/amice prior to infection resulted in the generation of FV-specific CD4+Th1 responses. This novel helper effect of CD8+T cells could be an important mechanism in the development of CD4+Th1 responses following vaccinations that induce CD8+CTL responses. The ability of MHC class I genes to facilitate CD4+Th1 development could also be considerable evolutionary advantage by allowing a wider variety of MHC genotypes to generate protective immune responses against intracellular pathogens.
Proteolytic Processing of a Serotype 8 Human Astrovirus ORF2 Polyprotein
Authors: Méndez Ernesto , Fernández-Luna Teresa , López Susana , Méndez-Toss Martha , Arias Carlos F. 
Published: July 2002

ABSTRACT
Astroviruses require the proteolytic cleavage of the capsid protein to infect the host cell. Here we describe the processing pathway of the primary translation product of the structural polyprotein (ORF2) encoded by a human astrovirus serotype 8 (strain Yuc8). The primary translation product of ORF2 is of approximately 90 kDa, which is subsequently cleaved to yield a 70-kDa protein (VP70) which is assembled into the viral particles. Limited trypsin treatment of purified particles containing VP70 results in the generation of polypeptides VP41 and VP28, which are then further processed to proteins of 38.5, 35, and 34 kDa and 27, 26, and 25 kDa, respectively. VP34, VP27 and VP25 are the predominant proteins in fully cleaved virions, which correlate with the highest level of infectivity. Processing of the VP41 protein to yield VP38.5 to VP34 polypeptides occurred at its carboxy terminus, as suggested by immunoblot analysis using hyperimmune sera to different regions of the ORF2, while processing of VP28 to generate VP27 and VP25 occurred at its carboxy and amino terminus, respectively, as determined by immunoblot, as well as by N-terminal sequencing of those products. Based on these data, the processing pathway for the 90-kDa primary product of astrovirus Yuc8 ORF2 is presented.
RelA-Associated Inhibitor Blocks Transcription of Human Immunodeficiency Virus Type 1 by Inhibiting NF-κB and Sp1 Actions
Authors: Takada Norio , Sanda Takaomi , Okamoto Hiroshi , Yang Jian-Ping , Asamitsu Kaori , Sarol Lilen , Kimura Genjiro , Uranishi Hiroaki , Tetsuka Toshifumi , Okamoto Takashi 
Published: July 2002

ABSTRACT
RelA-associated inhibitor (RAI) is an inhibitor of nuclear factor κB (NF-κB) newly identified by yeast two-hybrid screen as an interacting protein of the p65 (RelA) subunit. In this study, we attempted to examine the effect of RAI on transcription and replication of human immunodeficiency virus type 1 (HIV-1). We found that RAI inhibited gene expression from the HIV-1 long terminal repeat (LTR) even at the basal level. Upon in vitro DNA-binding reactions, RAI could directly block the DNA-binding of p65 subunit of NF-κB but not that of the p50 subunit or AP1. We found that RAI could also inhibit the DNA-binding of Sp1 and thus inhibit the basal HIV-1 promoter activity. We further examined the effects of RAI on Sp1 and found that RAI colocalizes with Sp1 in the nucleus and interacts with Sp1 in vitro and in vivo. Moreover, we found that RAI efficiently blocked the HIV-1 replication when cotransfected with a full-length HIV-1 clone. These findings indicate that RAI acts as an efficient inhibitor of HIV-1 gene expression in which both NF-κB and Sp1 play major roles.
Bacteriophage PM2 Has a Protein Capsid Surrounding a Spherical Proteinaceous Lipid Core
Authors: Kivelä Hanna M. , Kalkkinen Nisse , Bamford Dennis H. 
Published: July 2002

ABSTRACT

The marine double-stranded DNA (dsDNA) bacteriophage PM2, studied since 1968, is the type organism of the family
Corticoviridae
, infecting two gram-negative
Pseudoalteromonas
species. The virion contains a membrane underneath an icosahedral protein capsid composed of two structural proteins. The purified major capsid protein, P2, appears as a trimer, and the receptor binding protein, P1, appears as a monomer. The C-terminal part of P1 is distal and is responsible for receptor binding activity. The rest of the structural proteins are associated with the internal phospholipid membrane enclosing the viral genome. This internal particle is designated the lipid core. The overall structural organization of phage PM2 resembles that of dsDNA bacteriophage PRD1, the type organism of the family
Tectiviridae
.
Characterization of a Polytropic Murine Leukemia Virus Proviral Sequence Associated with the Virus Resistance GeneRmcfof DBA/2 Mice
Authors: Jung Yong Tae , Lyu Myung Soo , Buckler-White Alicia , Kozak Christine A. 
Published: July 2002

ABSTRACTThe DBA/2 mouseRmcfgene is responsible for in vivo and in vitro resistance to infection by the polytropic mink cell focus-forming (MCF) virus subgroup of murine leukemia viruses (MLVs). Previous studies suggested thatRmcfresistance is mediated by expression of an interfering MCF MLV envelope (Env) gene. To characterize thisenvgene, we examined resistance in crosses betweenRmcfrDBA/2 mice andMus castaneus, a species that lacks endogenous MCFenvsequences. In backcross progeny, inheritance ofRmcfresistance correlated with inheritance of a specific endogenous MCF virusenv-containing 4.6-kbEcoRI fragment. This fragment was present in the DBA/2N substrain withRmcf-mediated resistance but not in virus-susceptible DBA/2J substrain mice. This fragment contains a provirus with a 5′ long terminal repeat and the 5′ half ofenv; thegagandpolgenes have been partially deleted. The Env sequence is identical to that of a highly immunogenic viral glycoprotein expressed in the DBA/2 cell line L5178Y and closely resembles theenvgenes of modified polytropic proviruses. The coding sequence for the full-lengthRmcfEnv surface subunit was amplified from DNAs from virus-resistant backcross mice and was cloned into an expression vector. NIH 3T3 and BALB 3T3 cells stably transfected with this construct showed significant resistance to infection by MCF MLV but not by amphotropic MLV. This study identifies anRmcf-linked MCF provirus and indicates that, like the ecotropic virus resistance geneFv4,Rmcfmay mediate resistance through an interference mechanism.
Binding of Human Cytomegalovirus US2 to Major Histocompatibility Complex Class I and II Proteins Is Not Sufficient for Their Degradation
Authors: Chevalier Mathieu S. , Daniels Gwynn M. , Johnson David C. 
Published: July 2002

ABSTRACTHuman cytomegalovirus (HCMV) glycoprotein US2 causes degradation of major histocompatibility complex (MHC) class I heavy-chain (HC), class II DR-α and DM-α proteins, and HFE, a nonclassical MHC protein. In US2-expressing cells, MHC proteins present in the endoplasmic reticulum (ER) are degraded by cytosolic proteasomes. It appears that US2 binding triggers a normal cellular pathway by which misfolded or aberrant proteins are translocated from the ER to cytoplasmic proteasomes. To better understand how US2 binds MHC proteins and causes their degradation, we constructed a panel of US2 mutants. Mutants truncated from the N terminus as far as residue 40 or from the C terminus to amino acid 140 could bind to class I and class II proteins. Nevertheless, mutants lacking just the cytosolic tail (residues 187 to 199) were unable to cause degradation of both class I and II proteins. Chimeric proteins were constructed in which US2 sequences were replaced with homologous sequences from US3, an HCMV glycoprotein that can also bind to class I and II proteins. One of these US2/US3 chimeras bound to class II but not to class I, and a second bound class I HC better than wild-type US2. Therefore, US2 residues involved in the binding to MHC class I differ subtly from those involved in binding to class II proteins. Moreover, our results demonstrate that the binding of US2 to class I and II proteins is not sufficient to cause degradation of MHC proteins. The cytosolic tail of US2 and certain US2 lumenal sequences, which are not involved in binding to MHC proteins, are required for degradation. Our results are consistent with the hypothesis that US2 couples MHC proteins to components of the ER degradation pathway, enormously increasing the rate of degradation of MHC proteins.
Favorable and Unfavorable HLA Class I Alleles and Haplotypes in Zambians Predominantly Infected with Clade C Human Immunodeficiency Virus Type 1
Authors: Tang Jianming , Tang Shenghui , Lobashevsky Elena , Myracle Angela D. , Fideli Ulgen , Aldrovandi Grace , Allen Susan , Musonda Rosemary , Kaslow Richard A. ,   the Zambia-UAB HIV Research Project
Published: July 2002

ABSTRACTThe setpoint of viral RNA concentration (viral load [VL]) during chronic human immunodeficiency virus type 1 (HIV-1) infection reflects a virus-host equilibration closely related to CD8+cytotoxic T-lymphocyte (CTL) responses, which rely heavily on antigen presentation by the human major histocompatibility complex (MHC) (i.e., HLA) class I molecules. Differences in HIV-1 VL among 259 mostly clade C virus-infected individuals (137 females and 122 males) in the Zambia-UAB HIV Research Project (ZUHRP) were associated with several HLA class I alleles and haplotypes. In particular, general linear model analyses revealed lower log10VL among those with HLA allele B*57 (P= 0.002 [without correction]) previously implicated in favorable response and in those with HLA B*39 and A*30-Cw*03 (P= 0.002 to 0.016); the same analyses also demonstrated higher log10VL among individuals with A*02-Cw*16, A*23-B*14, and A*23-Cw*07 (P= 0.010 to 0.033). These HLA effects remained strong (P= 0.0002 to 0.075) after adjustment for age, gender, and duration of infection and persisted across three orders of VL categories (P= 0.001 to 0.084). In contrast, neither B*35 (n= 15) nor B*53 (n= 53) showed a clear disadvantage such as that reported elsewhere for these closely related alleles. Other HLA associations with unusually high (A*68, B*41, B*45, and Cw*16) or low (B*13, Cw*12, and Cw*18) VL were either unstable or reflected their tight linkage respecting disequilibria with other class I variants. The three consistently favorable HLA class I variants retained in multivariable models and in alternative analyses were present in 30.9% of subjects with the lowest (<10,000 copies per ml) and 3.1% of those with the highest (>100,000) VL. Clear differential distribution of HLA profiles according to level of viremia suggests important host genetic contribution to the pattern of immune control and escape during HIV-1 infection.
Characterization of a Novel Simian Immunodeficiency Virus with a
vpu
Gene from Greater Spot-Nosed Monkeys (
Cercopithecus nictitans
) Provides New Insights into Simian/Human Immunodeficiency Virus Phylogeny
Authors: Courgnaud Valérie , Salemi Marco , Pourrut Xavier , Mpoudi-Ngole Eitel , Abela Bernadette , Auzel Philippe , Bibollet-Ruche Frédéric , Hahn Beatrice , Vandamme Anne-Mieke , Delaporte Eric , Peeters Martine 
Published: July 2002

ABSTRACT

In the present study, we describe a new simian immunodeficiency virus (SIV), designated SIVgsn, naturally infecting greater spot-nosed monkeys (
Cercopithecus nictitans
) in Cameroon. Together with SIVsyk, SIVgsn represents the second virus isolated from a monkey belonging to the
Cercopithecus mitis
group of the
Cercopithecus
genus. Full-length genome sequence analysis of two SIVgsn strains, SIVgsn-99CM71 and SIVgsn-99CM166, revealed that despite the close phylogenetic relationship of their hosts, SIVgsn was highly divergent from SIVsyk. First of all, they differ in their genomic organization. SIVgsn codes for a
vpu
homologue, so far a unique feature of the members of the SIVcpz/human immunodeficiency virus type 1 (HIV-1) lineage, and detailed phylogenetic analyses of various regions of the viral genome indicated that SIVgsn might be a mosaic of sequences with different evolutionary histories. SIVgsn was related to SIVsyk in Gag and part of Pol and related to SIVcpz in Env, and the middle part of the genome did not cluster significantly with any of the known SIV lineages. When comparing the two SIVgsn Env sequences with that of SIVcpz, a remarkable conservation was seen in the V3 loop, indicating a possible common origin for the envelopes of these two viruses. The habitats of the two subspecies of chimpanzees infected by SIVcpz overlap the geographic ranges of greater spot-nosed monkeys and other monkey species, allowing cross-species transmission and recombination between coinfecting viruses. The complex genomic structure of SIVgsn, the presence of a
vpu
gene, and its relatedness to SIVcpz in the envelope suggest a link between SIVgsn and SIVcpz and provide new insights about the origin of SIVcpz in chimpanzees.
Critical Role for Protein Tyrosine Phosphatase SHP-1 in Controlling Infection of Central Nervous System Glia and Demyelination by Theiler's Murine Encephalomyelitis Virus
Authors: Massa Paul T. , Ropka Stacie L. , Saha Sucharita , Fecenko Karen L. , Beuler Kathryn L. 
Published: July 2002

ABSTRACTWe previously characterized the expression and function of the protein tyrosine phosphatase SHP-1 in the glia of the central nervous system (CNS). In the present study, we describe the role of SHP-1 in virus infection of glia and virus-induced demyelination in the CNS. For in vivo studies, SHP-1-deficient mice and their normal littermates received an intracerebral inoculation of an attenuated strain of Theiler's murine encephalomyelitis virus (TMEV). At various times after infection, virus replication, TMEV antigen expression, and demyelination were monitored. It was found that the CNS of SHP-1-deficient mice uniquely displayed demyelination and contained substantially higher levels of virus than did that of normal littermate mice. Many infected astrocytes and oligodendrocytes were detected in both brains and spinal cords of SHP-1-deficient but not normal littermate mice, showing that the virus replicated and spread at a much higher rate in the glia of SHP-1-deficient animals. To ascertain whether the lack of SHP-1 in the glia was primarily responsible for these differences, glial samples from these mice were cultured in vitro and infected with TMEV. As in vivo, infected astrocytes and oligodendrocytes of SHP-1-deficient mice were much more numerous and produced more virus than did those of normal littermate mice. These findings indicate that SHP-1 is a critical factor in controlling virus replication in the CNS glia and virus-induced demyelination.
Kaposi's Sarcoma-Associated Herpesvirus-Induced Upregulation of the c-kitProto-Oncogene, as Identified by Gene Expression Profiling, Is Essential for the Transformation of Endothelial Cells
Authors: Moses Ashlee V. , Jarvis Michael A. , Raggo Camilo , Bell Yolanda C. , Ruhl Rebecca , Luukkonen B. G. Mattias , Griffith Diana J. , Wait Cecily L. , Druker Brian J. , Heinrich Michael C. , Nelson Jay A. , Früh Klaus 
Published: July 2002

ABSTRACTKaposi's sarcoma (KS), the most frequent malignancy afflicting AIDS patients, is characterized by spindle cell formation and vascularization. Infection with KS-associated herpesvirus (KSHV) is consistently observed in all forms of KS. Spindle cell formation can be replicated in vitro by infection of dermal microvascular endothelial cells (DMVEC) with KSHV. To study the molecular mechanism of this transformation, we compared RNA expression profiles of KSHV-infected and mock-infected DMVEC. Induction of several proto-oncogenes was observed, particularly the receptor tyrosine kinase c-kit. Consistent with increased c-Kit expression, KHSV-infected DMVEC displayed enhanced proliferation in response to the c-Kit ligand, stem cell factor (SCF). Inhibition of c-Kit activity with either a pharmacological inhibitor of c-Kit (STI 571) or a dominant-negative c-Kit protein reversed SCF-dependent proliferation. Importantly, inhibition of c-Kit signal transduction reversed the KSHV-induced morphological transformation of DMVEC. Furthermore, overexpression studies showed that c-Kit was sufficient to induce spindle cell formation. Together, these data demonstrate an essential role for c-Kit in KS tumorigenesis and reveal a target for pharmacological intervention.
Simian Virus 40 Large T Antigen and Two Independent T-Antigen Segments Sensitize Cells to Apoptosis following Genotoxic Damage
Authors: Cole Sara L. , Tevethia M. J. 
Published: July 2002

ABSTRACT
The simian virus 40 (SV40) large tumor (T) antigen is sufficient to transform cells in cultures and induce tumors in experimental animals. Transformation of primary cells in cultures requires both overcoming growth arrest by stimulating the cell cycle and blocking cell death activities presumably activated by oncogene-mediated hyperproliferation signals. The study presented here examined the ability of specific regions and activities of T antigen to modulate apoptosis in cells treated with the genotoxic agent 5-fluorouracil (5-FU). The results showed that the expression of full-length T antigen rendered rat embryo fibroblasts (REF) sensitive to 5-FU-induced apoptosis. Thus, neither the p53-binding region nor the Bcl-2 homology region of T antigen was sufficient to prevent cell death induced by the DNA-damaging agent. T-antigen-mediated sensitization occurred independently of retinoblastoma protein or p53 and p300 binding. An N-terminal segment containing the first 127 T-antigen amino acids (T1-127) was sufficient to sensitize cells. A C-terminal segment consisting of T-antigen amino acids 251 to 708 (T251-708) also sensitized cells to 5-FU-induced apoptosis. This sensitization did not occur when T251-708 was targeted to the nucleus by inclusion of the SV40 nuclear localization signal. The introduction of mutations into the T-antigen J domain resulted in mutation-specific and variable inhibition of apoptosis. This result suggested that either the structural or the functional integrity of the J domain is required to sensitize cells to apoptosis. Treatment of REF or REF expressing full-length T antigen, an N-terminal segment, or T251-708 resulted in increased expression of the p53-responsive MDM2 gene; apoptosis occurred through a p53-dependent pathway, as p53-null cells expressing these T antigens were resistant to 5-FU-induced apoptosis. Possible mechanisms involved in sensitizing cells to a p53-dependent apoptosis pathway in spite of the ability of T antigen to bind and inactivate the transcriptional transactivating activity of p53 are discussed.
Characterization of the Nuclear Localization Signal of the Borna Disease Virus Polymerase
Authors: Walker Michelle Portlance , Lipkin W. Ian 
Published: July 2002

ABSTRACT

Borna disease virus (BDV) is a nonsegmented negative-strand RNA virus that replicates and transcribes its genome in the nucleus of infected cells. BDV proteins involved in replication and transcription must pass through the nuclear envelope to associate with the genomic viral RNA. The RNA-dependent RNA polymerase (L) of BDV is postulated to be the catalytic enzyme of replication and transcription. We demonstrated previously that BDV L localizes to the nucleus of BDV-infected cells and L-transfected cells. Nuclear localization of the protein presupposes the presence of a nuclear localization signal (NLS) within its primary amino acid sequence or cotransport to the nucleus with another karyophilic protein. Because L localized to the nucleus in the absence of other viral proteins, we investigated the possibility that L contains an NLS. The minimal sequence required for nuclear localization of L was identified by analyzing the subcellular distribution of deletion mutants of L fused to a flag epitope tag or β
-
galactosidase. Although the majority of the L fusion proteins localized to the cytoplasm of transfected BSR-T7 cells, a strong NLS (844RVVKLRIAP852) with basic and proline residues was identified. Mutation of this sequence resulted in cytoplasmic distribution of L, confirming that this sequence was necessary and sufficient to drive the nuclear localization of L.
Pulmonary epithelial response in the rat lung to instilled Montserrat respirable dusts and their major mineral components
Authors: Housley D G , Bérubé K A , Jones T P , Anderson S , Pooley F D , Richards R J 
Published: July 2002

Background:The Soufriere Hills, a stratovolcano on Montserrat, started erupting in July 1995, producing volcanic ash, both from dome collapse pyroclastic flows and phreatic explosions. The eruptions/ash resuspension result in high concentrations of suspended particulate matter in the atmosphere, which includes cristobalite, a mineral implicated in respiratory disorders.Aims:To conduct toxicological studies on characterised samples of ash, together with major components of the dust mixture (anorthite, cristobalite), and a bioreactive mineral control (DQ12 quartz).Methods:Rats were challenged with a single mass (1 mg) dose of particles via intratracheal instillation and groups sacrificed at one, three, and nine weeks. Acute bioreactivity of the particles was assessed by increases in lung permeability and inflammation, changes in epithelial cell markers, and increase in the size of bronchothoracic lymph nodes.Results:Data indicated that respirable ash derived from pyroclastic flows (20.1% cristobalite) or phreatic explosion (8.6% cristobalite) had minimal bioreactivity in the lung. Anorthite showed low bioreactivity, in contrast to pure cristobalite, which showed progressive increases in lung damage.Conclusion:Results suggests that either the percentage mass of cristobalite particles present in Montserrat ash was not sufficient as a catalyst in the lung environment, or its surface reactivity was masked by the non-reactive volcanic glass components during the process of ash formation.
Proposed use of adrenaline (epinephrine) in anaphylaxis and related conditions: a study of senior house officers starting accident and emergency posts
Authors: Gompels L L , Bethune C , Johnston S L , Gompels M M 
Published: July 2002

Abstract
Senior house officers (SHOs) (n=78) at the start of their accident and emergency (A&E) post were given an anonymous five case history questionnaire, containing one case of true anaphylaxis, and asked to complete the medication they would prescribe. In the case of anaphylaxis, 100% would administer adrenaline (epinephrine) but 55% would do so by the incorrect route. In the remaining cases, 10%–56% would be prepared to administer adrenaline inappropriately. Only 5% were able to indicate the correct route and dose of adrenaline according to Resuscitation Council guidelines (UK). This has implications for training as the survey took place before the start of the A&E posting. Anaphylaxis is over-diagnosed and poorly treated despite Resuscitation Council guidelines.