YS01 Protective Effect of HLA‐B57 on HCV Genotype 2 Infection in a West African Population

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Background Recovery from Hepatitis C virus (HCV) infection is considered infrequent (<20%) in western populations but reaches 50% in West Africa where genotype 2 infection is predominant (Candotti J Virol 2003; 77: 7914).Aim To investigate cellular immune responses as alternative diagnostic of HCV infection and the possible involvement of viral or host genetic factors in recovery.Methods Samples from 104 Ghanaian blood donors screened with anti‐HCV rapid tests and enzyme immunoassay were collected between 2000 and 2005. HCV antibody screening was confirmed using genotype 2 recombinant core, E2 and NS3 proteins by Western blot. HCV viral load and genotype were determined. Cellular response to recombinant HCV genotype 2 proteins was tested by IFN gamma ELISpot on frozen cells. HLA genotype was determined by sequence specific oligonucleotide probes.Results A total of 104 donors were stratified in 37 chronic, 35 recovered infections and 32 false positive. 81% of subjects with chronic infections with RNA detected carried genotype 2 HCV RNA. Cellular immune response was investigated in 35 frozen peripheral blood mononuclear cell (PBMC) samples suitable for interferon‐gamma ELISpot assay. 12 confirmed recovered, one chronically infected and no false positive controls reacted to at least one recombinant protein. The magnitude of response was considerably higher in recovered cases. HLA‐B*57 was significantly more frequent in the group which had recovered from HCV infection compared with chronically infected subjects (P < 0.01, OR = 8.02). This allele is significantly more frequent in West Africa than in Europe or North America.Discussion and conclusions Cases classified as recovered by serological means were confirmed by the presence of T‐cells stimulated by viral proteins. Genotype 2 HCV tends to have lower viral load and better response to anti‐viral treatment suggesting that the local genotype might be more susceptible to immune control. However, genetic factors of the host might also influence the clinical outcome. It could be hypothesised that HLA‐B*5703 is the HLA molecule most efficient at presenting peptides from genotype 2 HCV in this population.