bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Cellular J-Domain Protein Modulates Polyprotein Processing and Cytopathogenicity of a Pestivirus
Authors: Rinck G. , Birghan C. , Harada T. , Meyers G. , Thiel H.-J. , Tautz N. 
Published: July 2002

ABSTRACTPestiviruses are positive-strand RNA viruses closely related to human hepatitis C virus. Gene expression of these viruses occurs via translation of a polyprotein, which is further processed by cellular and viral proteases. Here we report the formation of a stable complex between an as-yet-undescribed cellular J-domain protein, a member of the DnaJ-chaperone family, and pestiviral nonstructural protein NS2. Accordingly, we termed the cellular protein Jiv, for J-domain protein interacting with viral protein. Jiv has the potential to induce intransone specific processing step in the viral polyprotein, namely, cleavage of NS2-3. Efficient generation of its cleavage product NS3 has previously been shown to be obligatory for the cytopathogenicity of the pestiviruses. Regulated expression of Jiv in cells infected with noncytopathogenic bovine viral diarrhea virus disclosed a direct correlation between the intracellular level of Jiv, the extent of NS2-3 cleavage, and pestiviral cytopathogenicity.
Differential Infection of Polarized Epithelial Cell Lines by Sialic Acid-Dependent and Sialic Acid-Independent Rotavirus Strains
Authors: Ciarlet Max , Crawford Sue E. , Estes Mary K. 
Published: July 2002

ABSTRACTInfection of epithelial cells by some animal rotaviruses, but not human or most animal rotaviruses, requires the presence ofN-acetylneuraminic (sialic) acid (SA) on the cell surface for efficient infectivity. To further understand how rotaviruses enter susceptible cells, six different polarized epithelial cell lines, grown on permeable filter membrane supports containing 0.4-μm pores, were infected apically or basolaterally with SA-independent or SA-dependent rotaviruses. SA-independent rotaviruses applied apically or basolaterally were capable of efficiently infecting both sides of the epithelium of all six polarized cell lines tested, while SA-dependent rotaviruses only infected efficiently through the apical surface of five of the polarized cell lines tested. Regardless of the route of virus entry, SA-dependent and SA-independent rotaviruses were released almost exclusively from the apical domain of the plasma membrane of polarized cells before monolayer disruption or cell lysis. The transepithelial electrical resistance (TER) of cells decreased at the same time, irrespective of whether infection with SA-independent rotaviruses occurred apically or basolaterally. The TER of cells infected apically with SA-dependent rotaviruses decreased earlier than that of cells infected basolaterally. Rotavirus infection decreased TER before the appearance of cytopathic effect and cell death and resulted in an increase in the paracellular permeability to [3H]inulin as a function of loss of TER. The presence of SA residues on either the apical or basolateral side was determined using a Texas Red-conjugated lectin, wheat germ agglutinin (WGA), which binds SA residues. WGA bound exclusively to SA residues on the apical surface of the cells, confirming the requirement for SA residues on the apical cell membrane for efficient infectivity of SA-dependent rotaviruses. These results indicate that the rotavirus SA-independent cellular receptor is present on both sides of the epithelium, but SA-dependent and SA-independent rotavirus strains infect polarized epithelial cells by different mechanisms, which may be relevant for pathogenesis and selection of vaccine strains. Finally, rotavirus-induced alterations of the epithelial barrier and paracellular permeability suggest that common mechanisms of pathogenesis may exist between viral and bacterial pathogens of the intestinal tract.
Mucosal Transmission and Induction of Simian AIDS by CCR5-Specific Simian/Human Immunodeficiency Virus SHIV
SF162P3
Authors: Harouse Janet M. , Gettie Agegnehu , Eshetu Tadesse , Tan Rei Chin How , Bohm Rudolf , Blanchard James , Baskin Gary , Cheng-Mayer Cecilia 
Published: July 2002

ABSTRACT

Nonhuman primate models are increasingly used in the screening of candidate AIDS vaccine and immunization strategies for advancement to large-scale human trials. The predictive value of such macaque studies is largely dependent upon the fidelity of the model system in mimicking human immunodeficiency virus (HIV) type 1 infection in terms of viral transmission, replication, and pathogenesis. Herein, we describe the efficient mucosal transmission of a CCR5-specific chimeric simian/human immunodeficiency virus, SHIV
SF162P3
. Female rhesus macaques were infected with SHIV
SF162P3
after a single atraumatic application to the cervicovaginal mucosa. The disease course of SHIV
SF162P3
-infected monkeys is similar and as varied as natural HIV infection in terms of viral replication, gradual loss of CD4
+
peripheral blood mononuclear cells, and the development of simian AIDS-defining opportunistic infections. The SHIV
SF162P3
/macaque model should facilitate direct preclinical assessment of HIV vaccine strategies in addition to antiviral compounds directed towards envelope target cell interactions. Furthermore, this controlled model provides the setting to investigate immunologic responses and putative host-specific susceptibility factors that alter viral transmission and subsequent disease progression.
Exposure of Hepatitis C Virus (HCV) RNA-Positive Recipients to HCV RNA-Positive Blood Donors Results in Rapid Predominance of a Single Donor Strain and Exclusion and/or Suppression of the Recipient Strain
Authors: Laskus Tomasz , Wang Lian-Fu , Radkowski Marek , Vargas Hugo , Nowicki Marek , Wilkinson Jeffrey , Rakela Jorge 
Published: July 2002

ABSTRACTWe have analyzed three cases of hepatitis C virus (HCV)-infected recipients who received blood from HCV-infected donors. Two recipients were exposed to two different HCV RNA-positive donors, and one was exposed to a single donor. All parental genomes from the actual infecting units of blood and the recipients were defined, and their presence in the follow-up serum samples was determined using sensitive strain-specific assays. The strain from one of the donors was found to predominate in all recipients' serum samples collected throughout the follow-up period of 10 to 30 months. In two recipients exposed to two infected donors, the strain from the second donor was occasionally found at very low level. However, the original recipients' strains were not detected. Our observations show that HCV-infected individuals can be superinfected with different strains, and this event may lead to eradication or suppression of the original infecting strain. Furthermore, our findings demonstrate that simultaneous exposure to multiple HCV strains may result in concomitant infection by more than one strain, although a single strain could rapidly establish its dominance. The results of the present study suggest the existence of competition among infecting HCV strains which determines the ultimate outcome of multiple HCV exposure.
Egress of Alphaherpesviruses: Comparative Ultrastructural Study
Authors: Granzow Harald , Klupp Barbara G. , Fuchs Walter , Veits Jutta , Osterrieder Nikolaus , Mettenleiter Thomas C. 
Published: July 2002

ABSTRACTEgress of four important alphaherpesviruses, equine herpesvirus 1 (EHV-1), herpes simplex virus type 1 (HSV-1), infectious laryngotracheitis virus (ILTV), and pseudorabies virus (PrV), was investigated by electron microscopy of infected cell lines of different origins. In all virus-cell systems analyzed, similar observations were made concerning the different stages of virion morphogenesis. After intranuclear assembly, nucleocapsids bud at the inner leaflet of the nuclear membrane, resulting in enveloped particles in the perinuclear space that contain a sharply bordered rim of tegument and a smooth envelope surface. Egress from the perinuclear cisterna primarily occurs by fusion of the primary envelope with the outer leaflet of the nuclear membrane, which has been visualized for HSV-1 and EHV-1 for the first time. The resulting intracytoplasmic naked nucleocapsids are enveloped at membranes of thetrans-Golgi network (TGN), as shown by immunogold labeling with a TGN-specific antiserum. Virions containing their final envelope differ in morphology from particles within the perinuclear cisterna by visible surface projections and a diffuse tegument. Particularly striking was the addition of a large amount of tegument material to ILTV capsids in the cytoplasm. Extracellular virions were morphologically identical to virions within Golgi-derived vesicles, but distinct from virions in the perinuclear space. Studies with gB- and gH-deleted PrV mutants indicated that these two glycoproteins, which are essential for virus entry and direct cell-to-cell spread, are dispensable for egress. Taken together, our studies indicate that the deenvelopment-reenvelopment process of herpesvirus maturation also occurs in EHV-1, HSV-1, and ILTV and that membrane fusion processes occurring during egress are substantially different from those during entry and direct viral cell-to-cell spread.
Role of the Cytoplasmic Domain of the β-Subunit of Integrin αvβ6 in Infection by Foot-and-Mouth Disease Virus
Authors: Miller Laura C. , Blakemore Wendy , Sheppard Dean , Atakilit Amha , King Andrew M. Q. , Jackson Terry 
Published: July 2002

ABSTRACTField isolates of foot-and-mouth disease virus (FMDV) are believed to use RGD-dependent integrins as cellular receptors in vivo. Using SW480 cell transfectants, we have recently established that one such integrin, αvβ6, functions as a receptor for FMDV. This integrin was shown to function as a receptor for virus attachment. However, it was not known if the αvβ6 receptor itself participated in the events that follow virus binding to the host cell. In the present study, we investigated the effects of various deletion mutations in the β6 cytoplasmic domain on infection. Our results show that although loss of the β6 cytoplasmic domain has little effect on virus binding, this domain is essential for infection, indicating a critical role in postattachment events. The importance of endosomal acidification in αvβ6-mediated infection was confirmed by experiments showing that infection could be blocked by concanamycin A, a specific inhibitor of the vacuolar ATPase.
Complementation of Vaccinia Virus Lacking the Double-Stranded RNA-Binding Protein Gene E3L by Human Cytomegalovirus
Authors: Child Stephanie J. , Jarrahian Sohail , Harper Victoria M. , Geballe Adam P. 
Published: July 2002

ABSTRACT
The cellular response to viral infection often includes activation of pathways that shut off protein synthesis and thereby inhibit viral replication. In order to enable efficient replication, many viruses carry genes such as the E3L gene of vaccinia virus that counteract these host antiviral pathways. Vaccinia virus from which the E3L gene has been deleted (VVΔE3L) is highly sensitive to interferon and exhibits a restricted host range, replicating very inefficiently in many cell types, including human fibroblast and U373MG cells. To determine whether human cytomegalovirus (CMV) has a mechanism for preventing translational shutoff, we evaluated the ability of CMV to complement the deficiencies in replication and protein synthesis associated with VVΔE3L. CMV, but not UV-inactivated CMV, rescued VVΔE3L late gene expression and replication. Thus, complementation of the VVΔE3L defect appears to depend on de novo CMV gene expression and is not likely a result of CMV binding to the cell receptor or of a virion structural protein. CMV rescued VVΔE3L late gene expression even in the presence of ganciclovir, indicating that CMV late gene expression is not required for complementation of VVΔE3L. The striking decrease in overall translation after infection with VVΔE3L was prevented by prior infection with CMV. Finally, CMV blocked both the induction of eukaryotic initiation factor 2α (eIF2α) phosphorylation and activation of RNase L by VVΔE3L. These results suggest that CMV has one or more immediate-early or early genes that ensure maintenance of a high protein synthetic capacity during infection by preventing activation of the PKR/eIF2α phosphorylation and 2-5A oligoadenylate synthetase/RNase L pathways.
Caveolar Endocytosis of Simian Virus 40 Is Followed by Brefeldin A-Sensitive Transport to the Endoplasmic Reticulum, Where the Virus Disassembles
Authors: Norkin Leonard C. , Anderson Howard A. , Wolfrom Scott A. , Oppenheim Ariella 
Published: July 2002

ABSTRACT
Simian virus 40 (SV40) enters cells by atypical endocytosis mediated by caveolae that transports the virus to the endoplasmic reticulum (ER) instead of to the endosomal-lysosomal compartment, which is the usual destination for viruses and other cargo that enter by endocytosis. We show here that SV4O is transported to the ER via an intermediate compartment that contains β-COP, which is best known as a component of the COPI coatamer complexes that are required for the retrograde retrieval pathway from the Golgi to the ER. Additionally, transport of SV40 to the ER, as well as infection, is sensitive to brefeldin A. This drug acts by specifically inhibiting the ARF1 GTPase, which is known to regulate assembly of COPI coat complexes on Golgi cisternae. Moreover, some β-COP colocalizes with intracellular caveolin-1, which was previously shown to be present on a new organelle (termed the caveosome) that is an intermediate in the transport of SV40 to the ER (L. Pelkmans, J. Kartenbeck, and A. Helenius, Nat. Cell Biol. 3:473-483, 2001). We also show that the internal SV40 capsid proteins VP2 and VP3 become accessible to immunostaining starting at about 5 h. Most of that immunostaining overlays the ER, with some appearing outside of the ER. In contrast, immunostaining with anti-SV40 antisera remains confined to the ER.
Highly Pathogenic Simian Immunodeficiency Virus mne Variants That Emerge during the Course of Infection Evolve Enhanced Infectivity and the Ability To Downregulate CD4 but Not Class I Major Histocompatibility Complex Antigens
Authors: Patel Parul G. , Yu Kimata Monica T. , Biggins Julia E. , Wilson Joelle M. , Kimata Jason T. 
Published: July 2002

ABSTRACT

The replicative, cytopathic, and antigenic properties of simian immunodeficiency virus (SIV) variants influence its replication efficiency in vivo. To further define the viral properties and determinants that may be important for high-level replication in vivo and progression to AIDS, we compared a minimally pathogenic SIVmne molecular clone with two highly pathogenic variants cloned from late stages of infection. Both variants had evolved greater infectivity than the parental clone due to mutations in
nef
. Interestingly, a
pol
determinant in one of the highly pathogenic variants also contributed to its increased infectivity. Furthermore, because replication in vivo may also be influenced by the ability of a virus to evade the cellular immune response of the host, we examined whether the variants were more capable of downregulating surface expression of class I major histocompatibility complex (MHC). Decreased MHC class I expression was not observed in cells infected with any of the viruses. Furthermore, the Nef proteins of the highly pathogenic variants only slightly reduced surface MHC class I expression in transfected cells, although they efficiently downregulated CD4. Together, these data demonstrate that mutations which can enhance viral infectivity, as well as CD4 downregulation, may be important for efficient replication of SIV in the host. However, Nef-mediated reduction of MHC class I expression does not appear to be critical for the increased in vivo replicative ability of highly pathogenic late variants.
Human T-Cell Leukemia Virus Type 2 (HTLV-2) Tax Protein Transforms a Rat Fibroblast Cell Line but Less Efficiently than HTLV-1 Tax
Authors: Endo Keiichi , Hirata Akira , Iwai Kousuke , Sakurai Mamoru , Fukushi Masaya , Oie Masayasu , Higuchi Masaya , Hall William W. , Gejyo Fumitake , Fujii Masahiro 
Published: July 2002

ABSTRACT
Human T-cell leukemia virus type 1 (HTLV-1) and HTLV-2 are retroviruses with similar biological properties. Whereas HTLV-1 is the causative agent of an aggressive T-cell leukemia, HTLV-2 has been associated with only a few cases of lymphoproliferative disorders. Tax1 and Tax2 are the transcriptional activators of HTLV-1 and HTLV-2, respectively. Here we show that Tax2 transformed a Rat-1 fibroblast cell line to form colonies in soft agar, but the size and number of the colonies were lower than those of Tax1. Use of a chimeric Tax protein showed that the C-terminal amino acids 300 to 353 were responsible for the high transforming activity of Tax1. Activation of cellular genes by Tax1 through transcription factor NF-κB is reportedly essential for the transformation of Rat-1 cells. Tax2 also activated the transcription through NF-κB in Rat-1 cells, and such activity was equivalent to that induced by Tax1. Thus, the high transforming activity of Tax1 is mediated by mechanisms other than NF-κB activation. Our results showed that Tax2 has a lower transforming activity than Tax1 and suggest that the high transforming activity of Tax1 is involved in the leukemogenic property of HTLV-1.
Identification of Neutralizing and Nonneutralizing Epitopes in the Porcine Reproductive and Respiratory Syndrome Virus GP5 Ectodomain
Authors: Ostrowski M. , Galeota J. A. , Jar A. M. , Platt K. B. , Osorio F. A. , Lopez O. J. 
Published: July 2002

ABSTRACTAfter infection of swine with porcine reproductive and respiratory syndrome virus (PRRSV), there is a rapid rise of PRRSV-specific nonneutralizing antibodies (NNA), while neutralizing antibodies (NA) are detectable not sooner than 3 weeks later. To characterize neutralizing epitopes, we selected phages from a 12-mer phage display library using anti-PRRSV neutralizing monoclonal antibody (MAb) ISU25-C1. In addition, phages carrying peptides recognized by swine antibodies with high seroneutralizing titer were isolated after subtracting from the library those clones binding to swine anti-PRRSV serum with no neutralizing activity. Two epitopes located in the ectodomain of PRRSV GP5 were identified. One of these epitopes, which we named epitope B, was recognized both by neutralizing MAb ISU25-C1 and swine neutralizing serum (NS) but not by swine nonneutralizing serum (NNS), indicating that it is a neutralizing epitope. Epitope B is sequential, conserved among isolates, and not immunodominant. Antibodies directed against it are detected in serum late after infection. In contrast, the other epitope, which we named epitope A, is hypervariable and immunodominant. Antibodies against it appear early after infection with PRRSV. This epitope is recognized by swine NNA but is not recognized by either neutralizing MAb ISU25-C1 or swine NA, indicating that it is not involved in PRRSV neutralization. During infection with PRRSV, epitope A may act as a decoy, eliciting most of the antibodies directed to GP5 and delaying the induction of NA against epitope B for at least 3 weeks. These results are relevant to the design of vaccines against PRRSV.
Highly Stable Trimers Formed by Human Immunodeficiency Virus Type 1 Envelope Glycoproteins Fused with the Trimeric Motif of T4 Bacteriophage Fibritin
Authors: Yang Xinzhen , Lee Juliette , Mahony Erin M. , Kwong Peter D. , Wyatt Richard , Sodroski Joseph 
Published: July 2002

ABSTRACTThe envelope glycoproteins of human immunodeficiency virus type 1 (HIV-1) function as a trimer composed of three gp120 exterior glycoproteins and three gp41 transmembrane proteins. Soluble gp140 glycoproteins composed of the uncleaved ectodomains of gp120 and gp41 form unstable, heterogeneous oligomers, but soluble gp140 trimers can be stabilized by fusion with a C-terminal, trimeric GCN4 motif (X. Yang et al., J. Virol. 74:5716-5725, 2000). To understand the influence of the C-terminal trimerization domain on the properties of soluble HIV-1 envelope glycoprotein trimers, uncleaved, soluble gp140 glycoproteins were stabilized by fusion with another trimeric motif derived from T4 bacteriophage fibritin. The fibritin construct was more stable to heat and reducing conditions than the GCN4 construct. Both GCN4- and fibritin-stabilized soluble gp140 glycoproteins exhibited patterns of neutralizing and nonneutralizing antibody binding expected for the functional envelope glycoprotein spike. Of note, two potently neutralizing antibodies, immunoglobulin G1b12 and 2G12, exhibited the greatest recognition of the stabilized, soluble trimers, relative to recognition of the gp120 monomer. The observed similarities between the GCN4 and fibritin constructs indicate that the HIV-1 envelope glycoprotein ectodomains dictate many of the antigenic and structural features of these fusion proteins. The melting temperatures and ligand recognition properties of the GCN4- and fibritin-stabilized soluble gp140 glycoproteins suggest that these molecules assume conformations distinct from that of the fusion-active, six-helix bundle.
The trunk muscles of elite oarsmen
Authors: McGregor A H , Anderton L , Gedroyc W M W 
Published: July 2002

Objectives:To investigate the trunk strength of elite rowers and the impact of low back pain on these measures in order to determine if asymmetries or weakness were present.Methods:Twenty two elite rowers were recruited: 13 reported previous low back pain, five current low back pain, and the remainder had no history of low back pain. All subjects were scanned during simulated rowing in an interventional open magnetic resonance imaging scanner. In each simulated rowing position, axial scans were obtained at the level of the L4–5 and L5–S1 disc interspace to determine the cross sectional area of the posterior trunk muscles.Results:Considerable differences were observed between the three groups of rowers. In contrast with expectations and previous literature, the trunk muscles of rowers with low back pain had significantly larger cross sectional areas (p<0.001). No left/right asymmetries were observed and no differences between oarside and non-oarside in terms of muscle cross sectional area.Conclusion:These findings suggest that low back pain in rowers does not arise as a result of muscle weakness.
The prognostic value of quality of life scores during treatment for oesophageal cancer
Authors: Blazeby J M , Brookes S T , Alderson D 
Published: July 2002

BACKGROUNDQuality of life (QL) data are useful to evaluate the effectiveness of treatment. Accumulating evidence suggests that QL data may predict survival.AIMSIn this study we investigated if baseline QL scores and changes in QL scores before and after intervention are prognostic for patients with oesophageal cancer.PATIENTSBetween 1993 and 1995, 92 consecutive new patients with oesophageal cancer were studied; 89 were followed until death or the end of the study period (survival of seven patients was censored in May 1999).METHODSAll patients completed the European Organisation for Research and Treatment of Cancer (EORTC) core questionnaire (EORTC QLQ-C30) and the dysphagia scale of the oesophageal module (EORTC QLQ-OES24) before treatment and at regular intervals throughout the study. Cox's proportional hazards models assessed the impact of baseline QL variables and changes in QL scores on survival.RESULTSCox's proportional hazards models, adjusting for associations between QL scores, age, and TNM stage, found that physical function at baseline was significantly associated with survival (p=0.002). An increase in physical function score of 10 points corresponded to a 12% reduction in the likelihood of death at any given time (95% confidence intervals 4–18%). Further exploratory multivariable analyses suggested that improvement in emotional function six months after treatment was significantly related to longer survival (p<0.0001).CONCLUSIONSThese data provide evidence to support a relationship between patient rated scores of QL and survival. Further understanding of the associations between QL and clinical variables is needed.