Spontaneous Control of HCV Is Associated With Expression of HLA-B*57 and Preservation of Targeted Epitopes

BACKGROUND & AIMS: HLA class I alleles are linked to spontaneous control of hepatitis C virus (HCV) and human immunodeficiency virus-1, but for HCV the roles of particular alleles and corresponding CD8(+) T-cell responses remain incompletely defined. We aimed to determine the correlations between these alleles and natural outcomes of HCV and determine associated key T-cell responses. METHODS: In a cohort of HCV individuals, we determined HLA class I alleles, HCV outcomes, T-cell responses, and examined sequence data for mutational changes within key epitopes. RESULTS: Carriage of HLA-B*57 was associated with a higher rate of viral clearance (risk ratio = 2.0; 95% confidence interval: 1.2-3.4), while HLA-B*08 was associated with a lower rate (risk ratio = 0.34; 95% confidence interval: 0.1-0.9]. Two HLA-B*57-restricted T-cell epitopes were targeted in spontaneous clearance; subjects with chronic viremia expressing HLA-B*57 harbored HCV strains with a high frequency of mutations in key residues. HLAB*57-mediated escape was supported by diminished immune recognition of these variants and acute HCV infection revealing viral evolution toward less recognized variants. Analysis of a genotype 1b strain from a single-source HCV outbreak in which HLA-B*57 was not protective revealed sequence variations that interfere with immunogenicity, thereby preventing HLA-B*57-mediated immune pressure. CONCLUSIONS: Our data indicate a role of HLA-B*57-restricted CD8(+) T-cell responses in mediating spontaneous clearance and evolution in HCV infection, and viral strains containing epitope variants that are less recognized abrogate the protective effects of HLA-B*57. The finding that HLAB*57-mediated antiviral immunity is associated with control of both human immunodeficiency virus-1 and HCV suggests a common shared mechanism of a successful immune response against persistent viruses.

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