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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: DAPN-PD1 is characterized as a novel and potent antiviral agent that combines the delivery of two active metabolites that are inhibitors of NS5B-mediated RNA polymerization in vitro and in vivo.
Abstract: Ribonucleoside analog inhibitors (rNAI) target the hepatitis C virus (HCV) RNA-dependent RNA polymerase nonstructural protein 5B (NS5B) and cause RNA chain termination. Here, we expand our studies on β-d-2'-C-methyl-2,6-diaminopurine-ribonucleotide (DAPN) phosphoramidate prodrug 1 (PD1) as a novel investigational inhibitor of HCV. DAPN-PD1 is metabolized intracellularly into two distinct bioactive nucleoside triphosphate (TP) analogs. The first metabolite, 2'-C-methyl-GTP, is a well-characterized inhibitor of NS5B polymerase, whereas the second metabolite, 2'-C-methyl-DAPN-TP, behaves as an adenosine base analog. In vitro assays suggest that both metabolites are inhibitors of NS5B-mediated RNA polymerization. Additional factors, such as rNAI-TP incorporation efficiencies, intracellular rNAI-TP levels, and competition with natural ribonucleotides, were examined in order to further characterize the potential role of each nucleotide metabolite in vivo Finally, we found that although both 2'-C-methyl-GTP and 2'-C-methyl-DAPN-TP were weak substrates for human mitochondrial RNA (mtRNA) polymerase (POLRMT) in vitro, DAPN-PD1 did not cause off-target inhibition of mtRNA transcription in Huh-7 cells. In contrast, administration of BMS-986094, which also generates 2'-C-methyl-GTP and previously has been associated with toxicity in humans, caused detectable inhibition of mtRNA transcription. Metabolism of BMS-986094 in Huh-7 cells leads to 87-fold higher levels of intracellular 2'-C-methyl-GTP than DAPN-PD1. Collectively, our data characterize DAPN-PD1 as a novel and potent antiviral agent that combines the delivery of two active metabolites.
9 citations
TL;DR: Sequence variation in the putative nonstructural region 5b (NS5b) of hepatitis C virus was analyzed in China and indicated geographical differences in the distribution of individual HCV isolates, and the existence of a local variant in the same subtype.
Abstract: Sequence variation in the putative nonstructural region 5b (NS5b) of hepatitis C virus (HCV) was analyzed in China. Complementary DNA fragments from sera of 49 Chinese patients were amplified by polymerase chain reaction (PCR) and the products were cloned and sequenced. Based on the comparison in NS5b of 33 clones of genotype 1b and 16 clones of genotype 2a, Chinese isolates of HCV belong to the same subtype as HCV-J, and HC-J6 from Japan. There does exist, however, some heterogeneity in the primary structure of the nucleotide acid. Higher homology was found among Chinese isolates than among Chinese isolates and Japanese isolates. Furthermore, among Chinese isolates, we found some conserved nucleotide acid positions different from those of Japanese isolates. Comparison of average homology among the 33 clones of genotype 1b and the 16 clones of genotype 2a indicated that the average homology among genotype 2a was lower than that among genotype 1b. In addition, a deletion of three nucleotide acids and a frame-shift, resulting in the introduction of an in-frame stop codon, were first observed in the NS5b region. These results indicated geographical differences in the distribution of individual HCV isolates, and the existence of a local variant in the same subtype. Our findings also suggested the need for further study on the sequence of genotype 2a, to improve diagnosis and help to advance the development of a vaccine.
9 citations
TL;DR: This study implicates that knowledge of the host HLA type and HCV subtype/genotype can provide important information in defining personalized therapy, and highlights several hot spots in which HLA and drug selective pressure overlap.
9 citations
TL;DR: The results suggest that HCV variants with reduced susceptibility to RBV identified are preferential to genotype 2a, and site-directed mutagenesis of these mutations into the replicon indicated that Y2471H plays a role in the reduced susceptibility in RBV and leads to decrease in replication fitness.
9 citations
TL;DR: The synthesis and biological evaluation of a new series of benzimidazole derivatives as HCV NS5B inhibitors yielded compound 6b and 6d bearing 2-(2-benzyloxy)phenyl and 2-(4-methylbenzoloxy) phenyl moieties, respectively, as promising leads.
Abstract: Hepatitis C virus (HCV) NS5B polymerase is the key replicating protein of the virus and thus an attractive target for drug development. Here we report on the synthesis and biological evaluation of a new series of benzimidazole derivatives as HCV NS5B inhibitors. This yielded compound 6b and 6d bearing 2-(2-benzyloxy)phenyl and 2-(4- methylbenzyloxy)phenyl moieties, respectively, as promising leads. Binding mode of compound 6d in allosteric pocket (AP)-1 of NS5B will form the basis for future structure-activity relationship optimization.
9 citations