NS5A phosphorylation: its functional role in the life cycle of hepatitis C virus

Ferrocene-based inhibitors of hepatitis C virus replication that target NS5A with low picomolar in vitro antiviral activity

An unprecedented series of organometallic HCV (hepatitis C virus) NS5A (nonstructural 5A protein) replication complex inhibitors that incorporates a 1,1'-ferrocenediyl scaffold was explored. This scaffold introduces the elements of linear flexibility and non-planar topology that are unconventional for this class of inhibitors. Data from 2-D NMR spectroscopic analyses of these complexes in solution support an anti (unstacked) arrangement of the pharmacophoric groups. Several complexes demonstrate single-digit picomolar in vitro activity in an HCV genotype-1b replicon system. One complex to arise from this investigation (10a) exhibits exceptional picomolar activity against HCV genotype 1a and 1b replicons, low hepatocellular cytotoxicity, and good pharmacokinetic properties in rat.

Advances in drug development for hepatitis C

Chronic infection with hepatitis C virus (HCV) is a global public health burden. It has been only several decades since this virus was first identified. In the meantime, a lot of progress has been made in the fight against HCV. Although the development of pegylated interferon (PEG-IFN) and its combination with ribavirin (RBV) has significantly increased effectiveness of IFN-based treatment, candidate patients must be assessed for eligibility prior to the treatment due to side effects of the regimens and the rates of sustained virological response (SVR) were only around 50%. In 2011, the protease inhibitor (PI) Telaprevir was firstly approved as a direct-acting antiviral (DAA) for hepatitis C. The second generation of PIs was subsequently introduced and, by adding PI to Peg-IFN/RBV, the SVR rates were found to be raised to up to 80%. Further, with the recent approval of the NS5A inhibitors and the NS5B polymerase inhibitors and with the SVR rates reaching 90% or greater using IFN-free, DAA combination regimens, it is now expected that the majority of patients with chronic hepatitis C can be cured of infection in the near future.

Hepatitis C Virus Replication

Viruses use synthetic mechanism and organelles of the host cells to facilitate their replication and make new viruses. Host's ATP provides necessary energy. Hepatitis C virus (HCV) is a major cause of liver disease. Like other positive-strand RNA viruses, the HCV genome is thought to be synthesized by the replication complex, which consists of viral- and host cell-derived factors, in tight association with structurally rearranged vesicle-like cytoplasmic membranes. The virus-induced remodeling of subcellular membranes, which protect the viral RNA from nucleases in the cytoplasm, promotes efficient replication of HCV genome. The assembly of HCV particle involves interactions between viral structural and nonstructural proteins and pathways related to lipid metabolisms in a concerted fashion. Association of viral core protein, which forms the capsid, with lipid droplets appears to be a prerequisite for early steps of the assembly, which are closely linked with the viral genome replication. This review presents the recent progress in understanding the mechanisms for replication and assembly of HCV through its interactions with organelles or distinct organelle-like structures.