Search results for "Viral envelope"
showing 10 items of 102 documents
Non-redundant and redundant roles of cytomegalovirus gH/gL complexes in host organ entry and intra-tissue spread
2015
Herpesviruses form different gH/gL virion envelope glycoprotein complexes that serve as entry complexes for mediating viral cell-type tropism in vitro; their roles in vivo, however, remained speculative and can be addressed experimentally only in animal models. For murine cytomegalovirus two alternative gH/gL complexes, gH/gL/gO and gH/gL/MCK-2, have been identified. A limitation of studies on viral tropism in vivo has been the difficulty in distinguishing between infection initiation by viral entry into first-hit target cells and subsequent cell-to-cell spread within tissues. As a new strategy to dissect these two events, we used a gO-transcomplemented ΔgO mutant for providing the gH/gL/gO…
Tetraspanin CD151 Promotes Initial Events in Human Cytomegalovirus Infection.
2016
ABSTRACT Human cytomegalovirus (HCMV), a betaherpesvirus, can cause life-threatening disease in immunocompromised individuals. Viral envelope glycoproteins that mediate binding to and penetration into target cells have been identified previously. In contrast, cellular proteins supporting HCMV during entry are largely unknown. In order to systematically identify host genes affecting initial steps of HCMV infection, a targeted RNA interference screen of 96 cellular genes was performed in endothelial cells by use of a virus strain expressing the full set of known glycoprotein H and L (gH/gL) complexes. The approach yielded five proviral host factors from different protein families and eight an…
Signal sequences modulate the immunogenic performance of human hepatitis C virus E2 gene
2005
Abstract Envelope protein E2 of human hepatitis C virus (HCV) is an attractive component of a prototype HCV vaccine. Delivered by DNA immunogens, E2 evokes specific immune response of Th1-type, failing to induce either considerable antibody production, or T-helper cell proliferation. We aimed at modulating the immunogenic performance of E2 gene by changing the mode of protein expression in eukaryotic cells. Plasmids were constructed encoding full-length E2 and nonstructural protein 1 (p7) fused to either 13 or 38 C-terminal amino acids (aa) of HCV E1 that contain second hydrophobic segment of E1 stop-transfer signal, or a complete E1 stop-transfer signal with duplicated second hydrophobic s…
Enhanced Gene Delivery by Avidin-Displaying Baculovirus
2004
Flexible alteration of virus surface properties would be beneficial for enhanced and targeted gene delivery. A useful approach could be based on a high-affinity receptor–ligand pair, such as avidin and biotin. In this study, we have constructed an avidin-displaying baculovirus, Baavi. Avidin display was expected to enhance cell transduction due to the high positive charge of avidin in physiological pH and to provide a binding site for covering the virus with desired biotinylated ligands. Successful incorporation of avidin on the virus envelope was detected by immunoblotting and electron microscopy. Multiple biotin-binding sites per virus were detected with fluorescence-correlation spectrosc…
A Bimolecular Multicellular Complementation System for the Detection of Syncytium Formation: A New Methodology for the Identification of Nipah Virus …
2019
Fusion of viral and cellular membranes is a key step during the viral life cycle. Enveloped viruses trigger this process by means of specialized viral proteins expressed on their surface, the so-called viral fusion proteins. There are multiple assays to analyze the viral entry including those that focus on the cell-cell fusion induced by some viral proteins. These methods often rely on the identification of multinucleated cells (syncytium) as a result of cell membrane fusions. In this manuscript, we describe a novel methodology for the study of cell-cell fusion. Our approach, named Bimolecular Multicellular Complementation (BiMuC), provides an adjustable platform to qualitatively and quanti…
Evolutionary dynamics of the E1-E2 viral populations during combination therapy in non-responder patients chronically infected with hepatitis C virus…
2012
Abstract Half of the patients chronically infected with hepatitis C virus (HCV) genotype 1 fail to respond to pegylated interferon alpha (PEG-IFN) and ribavirin (RBV) therapy. This study assesses the effects of treatment on the evolution of the E1–E2 viral region in non-responder patients infected with HCV-1b. Twenty-three HCV-1b chronically infected patients were studied retrospectively, including 19 non-responders to PEG-IFN/RBV therapy (11 null-responders and 8 relapsers) in the study group, and 4 untreated patients in the control group. Genetic and phylogenetic analyses of the E1–E2 viral populations were performed at baseline and at the time of treatment failure to assess changes in ge…
Modulation of epitope-specific anti-hepatitis C virus E2 (anti-HCV/E2) antibodies by antiviral treatment
2006
The dynamic features of three specific anti-hepatitis C virus (HCV) antibody subpopulations directed against different conformational epitopes of the viral E2 protein (HCV/E2) have been evaluated in patients with primary and persistent HCV infection; the three subpopulations are present in patients infected with different HCV genotypes and have shown a different activity using a pseudovirus neutralization assay (antibodies e301 and e137 exhibiting high neutralizing activity, while antibody e509 enhancement of HCV infectivity). In sequential samples from five patients with primary HCV infection and different virological outcome, all samples tested negative with the single exception of the e5…
Two mutations in gB-1 and gD-1 of herpes simplex virus type 1 are involved in the "fusion from without" phenotype in different cell types.
1996
Previous studies have shown that certain strains of herpes simplex viruses type 1 (HSV-1) are able to induce “fusion from without” (FFWO) which means no transcription or translation of the viral genome happens. The main determinants for FFWO in BHK cells are mutations in the C-terminal part of gB-1. But single mutations in this part of the genome are not sufficient to transfer the FFWO phenotype also to Vero cells. Here, we report that FFWO of HSV strains indeed need additional mutations in the N-terminal part of gD in order to produce the FFWO phenotype in BHK and Vero cells. By marker transfer we are able to show that loss of mutations in the N-terminal part of gD influences the ability t…
Cloning and expression of the complement receptor glycoprotein C from Herpesvirus simiae (herpes B virus): protection from complement-mediated cell l…
2003
Simian herpes B virus (SHBV) is the herpes simplex virus (HSV) homologue for the species MACACA: Unlike in its natural host, and unlike other animal herpesviruses, SHBV causes high mortality in accidentally infected humans. SHBV-infected cells, like those infected with HSV-1 and equine herpesvirus types 1 and 4, express complement C3 receptor activity. To study immunoregulatory functions involved in susceptibility/resistance against interspecies transmission, the SHBV glycoprotein C (gC(SHBV)) gene (encoding 467 aa) was isolated. Sequence analysis revealed amino acid identity with gC proteins from HSV-2 (46.9 %), HSV-1 (44.5 %) and pseudorabies virus (21.2 %). Highly conserved cysteine resi…
Unequal distribution of RT-PCR artifacts along the E1-E2 region of Hepatitis C virus.
2009
Although viral variability studies have focused traditionally on consensus sequences, the relevance of molecular clone sequences for studying viral evolution at the intra-host level is being increasingly recognized. However, for this approach to be reliable, RT-PCR artifacts do not have to contribute excessively to the observed variability. Molecular clone sequences were obtained from an in vitro transcript to estimate the maximum error rate associated to RT-PCR for the Hepatitis C virus (HCV) E1-E2 region. On average, the frequency of RT-PCR errors was one order of magnitude lower than the level of intra-host genetic variability observed in samples from an HCV outbreak. However, RT-PCR err…