Alanine Scanning of the Hepatitis C Virus Core Protein Reveals Numerous Residues Essential for Production of Infectious Virus

Abstract

Hepatitis C virus (HCV) is an important human pathogen affecting an estimated 3% of the world's population. Recent advances have enabled in vitro propagation of the virus and allow assembly and egress to be investigated for the first time. As a component of the virion, the HCV core protein likely functions primarily in infectious virus production, although little is known about the determinants of this activity. To investigate the roles of core in the viral life cycle, we performed a comprehensive deletion and alanine scanning mutagenesis study of this protein in the context of a genotype 2a reporter virus. We have confirmed that core protein is essential for infectious virion production and have identified numerous residues required for this role. The infectivity of several assembly-defective core mutants could be rescued by compensatory mutations identified in p7 and NS2, suggesting genetic interactions with core and highlighting the importance of these nonstructural proteins in infectious virion morphogenesis.

Coordinated evolution of the hepatitis C virus

“…Several experiments have provided strong evidence of extensive epistasis in RNA viruses, confirming that during viral evolution certain substitutions at different sites may occur in a coordinated manner (7)(8)(9)(10)(11)(12). Experimental studies into the adaptation of genetically modified HCV genomes propagated in cell culture also have shown antagonistic epistatic interactions between deleterious mutations exhibited in the form of compensatory mutations (13)(14)(15). These results suggest the importance of long-range interactions among HCV constitutive amino acids that place additional constraints on HCV heterogeneity.…”

Sequential processing of hepatitis C virus core protein by host cell signal peptidase and signal peptide peptidase: a reassessment

“…However, only recently has a cell culture system been made available for HCV, supporting production of infectious virus in the Huh-7 human hepatoma cell line [4][5][6][7]. The HCV virion is considered to contain a capsid built of the virally encoded core protein, whose structural integrity has been shown to be critical for production of infectious virus in this model [8]. Beside its role as a structural component of the virion, HCV core protein has been assigned a number of regulatory functions and roles in the virus-induced pathogenesis, including liver steatogenesis and carcinogenesis [2,9,10].…”

Naturally occurring resistance mutations within the core and NS5B regions in hepatitis C genotypes, particularly genotype 5a, in South Africa

“…There is evidence that mutations in the BD2 region (contains the major binding site for NS5A) Fig.1. Hepatitis C core region 1-177 depicting the domains, functions, mutations identified in the study and known epitope regions can suppress binding to lipid droplets and reduce viral particle production, infectivity and release (Murray et al, 2007;Gawlik et al, 2014). The core: R70Q and L91M mutations have been associated with poor treatment response in genotype 1b infection to IFN (Akuta et al, 2010, Alhamlan et al, 2014, resistance to telaprevir combination therapy (Akuta et al, 2010), rate of progression to HCC (Araujo et al, 2014, Nakamoto et al, 2010, Khan et al, 2010, increased steatosis and hepatic oxidative stress (Tachi et al, 2010).…”