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NS5B
About: NS5B is a research topic. Over the lifetime, 1314 publications have been published within this topic receiving 59534 citations.
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TL;DR: No response group‐specific nucleotide or encoded amino acid substitution was identified in pretreatment serum samples from 40 patients with chronic HCV infection who were subsequently treated with IFN, and data suggest that these substitutions were selective rather than spontaneous events.
Abstract: Hepatitis C virus (HCV) is an RNA virus with the NS5B gene encoding an RNA-dependent RNA polymerase. Interferon-alpha (IFN-alpha) is effective against HCV and its effect is believed to be related to its antiviral activity. To determine whether sequence variations of the HCV NS5B region correlate with response to IFN therapy, pretreatment serum samples from 40 patients with chronic HCV infection who were subsequently treated with IFN (> or = 3 MU thrice weekly for 24 weeks) and had well-characterized biochemical responses were studied. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to generate an approximately 365-bp fragment from which nucleotide sequence and genotypes were determined. By comparing the nucleotide sequences and the encoded amino acid sequences of samples from each group, no response group-specific nucleotide or encoded amino acid substitution was identified. Most of the substitutions identified were synonymous (usually by changes at the third position of the codon). These data suggest that these substitutions were selective rather than spontaneous events. Of the few non-synonymous substitutions identified, none was correlated with subsequent response to IFN, either within or across genotypes.
9 citations
TL;DR: Data show that NS5B contains a B‐cell epitope located between amino acid residues 67 and 88, which interferes with the enzymatic function of NS4B, and Surprisingly, mAb recognizing the N‐terminal region ofNS5B inhibited RdRp activity in a dose‐dependent manner.
Abstract: Summary. The nonstructural 5B (NS5B) protein of hepatitis C virus (HCV) is an RNA-dependent RNA polymerase (RdRp) with a key role in HCV replication. To characterize the functional roles of NS5B in HCV replication, we produced a panel of 10 monoclonal antibodies (mAbs) directed against NS5B protein from mice immunized with functionally active RdRp. The epitopes of eight mAbs are localized in the middle region (amino acid 240–263) of NS5B protein. On the other hand, the epitopes of two mAbs are mapped to amino acids 67–88 at the N-terminus of NS5B protein. To examine the effects of mAbs on HCV-RNA replication, we performed in vitro RdRp assay using either the 3′-untranslated region (UTR) or the full-length of HCV-RNA as a template in the presence of each mAb. mAbs specific for the middle region of NS5B had no effect on RdRp activity. Surprisingly, mAb recognizing the N-terminal region of NS5B inhibited RdRp activity in a dose-dependent manner. We have confirmed the same result using the other subclass of mAb, whose epitope is also localized to the same N-terminal region of NS5B. These data show that NS5B contains a B-cell epitope located between amino acid residues 67 and 88. Binding of this epitope with an antibody interferes with the enzymatic function of NS5B.
9 citations
TL;DR: It is determined that the SLB platform enables functional reconstitution of membrane protein activity and can support functional studies of membrane-associated viral proteins engaged in critical biological activities.
Abstract: Therapeutic targeting of membrane-associated viral proteins is complicated by the challenge of investigating their enzymatic activities in the native membrane-bound state. To permit functional characterization of these proteins, we hypothesized that the supported lipid bilayer (SLB) can support in situ reconstitution of membrane-associated viral protein complexes. As proof-of-principle, we selected the hepatitis C virus (HCV) NS5B polymerase which is essential for HCV genome replication, and determined that the SLB platform enables functional reconstitution of membrane protein activity. Quartz crystal microbalance with dissipation (QCM-D) monitoring enabled label-free detection of full-length NS5B membrane association, its interaction with replicase subunits NS3, NS5A, and template RNA, and most importantly its RNA synthesis activity. This latter activity could be inhibited by the addition of candidate small molecule drugs. Collectively, our results demonstrate that the SLB platform can support functional...
9 citations
TL;DR: The synthesis and inhibitory activity of quinizarin derivatives towards both HCV NS5B polymerase and HIV-1 reverse transcriptase associated functions are reported and demonstrate that anthraquinone derivatives are promising anti-polymerase viral inhibitors.
Abstract: Human immunodeficiency virus 1 (HIV-1) and Hepatitis C virus (HCV) affect 60 and 170 million infected individuals worldwide, respectively, and co-infection by both pathogens is often observed. This represents a serious public health problem that requires the identification of new drugs targeting essential phases of the life cycle of these two viruses. In this report, the synthesis and inhibitory activity of quinizarin derivatives towards both HCV NS5B polymerase and HIV-1 reverse transcriptase associated functions are reported. Our results demonstrate that anthraquinone derivatives are promising anti-polymerase viral inhibitors.
9 citations
TL;DR: Two major genotypes (1 and 3), four subtypes and an inter-genotype recombinant strain (3a/1a) with a novel breakpoint in the NS4B coding region were found.
9 citations