A model for the study of hepatitis C virus entry.

The study of hepatitis C virus (HCV), a major cause of chronic liver disease, has been hampered by the lack of a cell culture system supporting its replication. Here, we have successfully generated infectious pseudo-particles that were assembled by displaying unmodified and functional HCV glycoproteins onto retroviral and lentiviral core particles. The presence of a green fluorescent protein marker gene packaged within these HCV pseudo-particles allowed reliable and fast determination of infectivity mediated by the HCV glycoproteins.

[Implication of mutation of hepatitis C virus 1b interferon sensitivity determining region(NS5A aa 2209-2248) response to interferon alpha therapy in patients with chronic hepatitis C].

Hepatitis C virus (HCV) isolates from 12 patients with chronic hepatitis C underwent the sequence analysis. Among the 12 patients, 9 obtained a complete response (CR), 2 partial response (PR) and 1 non--response (NR) after the treatment with IFN-alpha. The results showed that only single amino acid (aa) substitution in iIFN sensitivity determining region (ISDR) (aa 2213 and aa 2218) in 6 cases with CR was observed, while 3 cases of CR and all PR and NR cases had no aa mutation of ISDR.

Expression of hepatitis c virus proteins inhibits interferon alpha signaling in the liver of transgenic mice.

Unlabelled: BACKGROUND & AIMS Hepatitis C virus (HCV) is a major cause of chronic liver disease, cirrhosis, and hepatocellular carcinoma worldwide. The majority of patients treated with interferon alpha do not have a sustained response with clearance of the virus. The molecular mechanisms underlying interferon resistance are poorly understood.

Identification of the hepatitis C virus RNA replication complex in Huh-7 cells harboring subgenomic replicons.

Formation of a membrane-associated replication complex, composed of viral proteins, replicating RNA, and altered cellular membranes, is a characteristic feature of plus-strand RNA viruses. Here, we demonstrate the presence of a specific membrane alteration, designated the membranous web, that contains hepatitis C virus (HCV) nonstructural proteins, as well as viral plus-strand RNA, in Huh-7 cells harboring autonomously replicating subgenomic HCV RNAs. Metabolic labeling with 5-bromouridine 5'-triphosphate in the presence of actinomycin D revealed that the membranous web is the site of viral RNA synthesis and therefore represents the replication complex of HCV.

[Molecular virology of hepatitis C].

Hepatitis C virus (HCV) infection is a leading cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma worldwide. Here, we will briefly review current concepts of the molecular virology of hepatitis C. In vitro and in vivo models of HCV replication will be discussed in this context.

Interaction of hepatitis C virus proteins with host cell membranes and lipids.

For replication, viruses depend on specific components and energy supplies from the host cell. The main steps in the lifecycle of positive-strand RNA viruses depend on cellular membranes. Interest is increasing in studying the interactions between host cell membranes and viral proteins to understand how such viruses replicate their genome and produce infectious particles.

The hepatitis C virus RNA-dependent RNA polymerase membrane insertion sequence is a transmembrane segment.

The hepatitis C virus (HCV) RNA-dependent RNA polymerase (RdRp) belongs to a class of membrane proteins termed tail-anchored proteins. Here, we show that the HCV RdRp C-terminal membrane insertion sequence traverses the phospholipid bilayer as a transmembrane segment. Moreover, the HCV RdRp was found to be retained in the endoplasmic reticulum (ER) or an ER-derived modified compartment both following transient transfection and in the context of a subgenomic replicon.

Hepatitis C: molecular virology and antiviral targets.

Chronic hepatitis C is a leading cause of liver cirrhosis and hepatocellular carcinoma worldwide. Although current treatment options are limited, progress in understanding the molecular virology of hepatitis C has led to the identification of novel antiviral targets. Moreover, in vitro and in vivo model systems have been developed that allow systematic evaluation of new therapeutic strategies.

[Therapy of hepatitis C].

Hepatitis C virus (HCV) infection is a leading cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma worldwide. Here, we will briefly review current and evolving therapies for chronic hepatitis C. Standard therapy with (pegylated) interferon-alpha and ribavirin achieves sustained response rates of up to about 40% in genotype 1- and about 80% in genotype 2- and 3-infected patients.

Expression of hepatitis C virus proteins induces distinct membrane alterations including a candidate viral replication complex.

Plus-strand RNA viruses characteristically replicate their genome in association with altered cellular membranes. In the present study, the capacity of hepatitis C virus (HCV) proteins to elicit intracellular membrane alterations was investigated by expressing, in tetracycline-regulated cell lines, a comprehensive panel of HCV proteins individually as well as in the context of the entire HCV polyprotein. As visualized by electron microscopy (EM), expression of the combined structural proteins core-E1-E2-p7, the NS3-4A complex, and protein NS4B induced distinct membrane alterations.

An amino-terminal amphipathic alpha-helix mediates membrane association of the hepatitis C virus nonstructural protein 5A.

Hepatitis C virus (HCV) nonstructural protein 5A (NS5A), a phosphoprotein of unknown function, is believed to be a component of a membrane-associated viral replication complex. The determinants for membrane association of NS5A, however, have not been defined. By double label immunofluorescence analyses, NS5A was found to be associated with the endoplasmic reticulum (ER) or an ER-derived modified compartment both when expressed alone or in the context of the entire HCV polyprotein.

Hepatitis C: a concise review.

Chronic hepatitis C is a leading cause of liver cirrhosis and hepatocellular carcinoma worldwide. Current treatment options are limited, but recent progress in the understanding of the molecular virology of hepatitis C has led to the identification of novel targets for antiviral intervention. In addition, gene and immunotherapeutic strategies to inhibit hepatitis C virus (HCV) replication or gene expression and to enhance the cellular immune response against HCV are being explored.

Functional properties of a monoclonal antibody inhibiting the hepatitis C virus RNA-dependent RNA polymerase.

The hepatitis C virus (HCV) RNA-dependent RNA polymerase (RdRp), represented by nonstructural protein 5B (NS5B), has recently emerged as a promising target for antiviral intervention. Here, we describe the isolation, functional characterization, and molecular cloning of a monoclonal antibody (mAb) inhibiting the HCV RdRp. This mAb, designated 5B-12B7, binds with high affinity to a conformational epitope in the palm subdomain of the HCV RdRp and recognizes native NS5B expressed in the context of the entire HCV polyprotein or subgenomic replicons.

Hepatitis C: an update.

Hepatitis C virus (HCV) infection is a leading cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma worldwide. While current therapeutic options for hepatitis C are limited, recent progress in the understanding of the biology of HCV led to the identification of novel targets for antiviral intervention. In addition, molecular and immunotherapeutic strategies to inhibit HCV replication or gene expression and to enhance the cellular immune response against HCV are being explored.

Determinants for membrane association of the hepatitis C virus RNA-dependent RNA polymerase.

The hepatitis C virus (HCV) RNA-dependent RNA polymerase (RdRp), represented by nonstructural protein 5B (NS5B), is believed to form a membrane-associated RNA replication complex together with other nonstructural proteins and as yet unidentified host components. However, the determinants for membrane association of this essential viral enzyme have not been defined. By double label immunofluorescence analyses, NS5B was found in the endoplasmic reticulum (ER) or an ER-like modified compartment both when expressed alone or in the context of the entire HCV polyprotein.

The hepatitis C virus nonstructural protein 4B is an integral endoplasmic reticulum membrane protein.

The hepatitis C virus (HCV) nonstructural protein 4B (NS4B) is a relatively hydrophobic 27-kDa protein of unknown function. A tetracycline-regulated gene expression system, a novel monoclonal antibody, and in vitro transcription-translation were employed to investigate the subcellular localization and to characterize the membrane association of this viral protein. When expressed individually or in the context of the entire HCV polyprotein, NS4B was localized in the endoplasmic reticulum (ER), as shown by subcellular fractionation, immunofluorescence analyses, and double-label confocal laser scanning microscopy.