Mutations in NS5A region of hepatitis C virus genome correlate with presence of NS5A antibodies and response to interferon therapy for most common European hepatitis C virus genotypes

A part of the hepatitis C virus (HCV) nonstructural protein 5A (NS5A) amino acid sequence, designated as an interferon (IFN)-sensitive determining reg ion (ISDR), has been shown to be correlated with a response to IFN in Japan ese patients. We have shown previously that the presence of NS5A antibodies (Abs) detected by the INNOLIA test (IL-NS5A Ab) is also correlated with a response to IFN. The aim of this study was to investigate, in a wide range of patients, the possible relationship within the NS5A protein between the sequence of ISDR and that used in the INNOLIA test designated as ZUR. Serum samples from 52 patients infected by HCV genotypes 1, 2, and 3 were analyz ed before and after treatment. The patients were classified as nonresponder s (NRs), responder-relapsers (RRs), or long-term responders (LTRs). We ampl ified the NS5A region for 42 patients using polymerase chain reaction (PCR) , and these amplicons were sequenced directly The 10 remaining patients wer e analyzed using PCR with mutation-specific primers. No correlation was fou nd between the IL3R sequence of the HCV strains and the presence of the IL- NS5A Ab for all genotypes. However, for the subtype Ib, only 2 of II NR pat ients tested had an arginin in position 2218 within the ISDR versus 3 of 3 LTR and 10 of 13 RR patients. All patients with R-2218 had IL-NS5A Ab. For the genotype 1a, 2 of 2 LTR and 1 of 3 RR were mutated in position 2216-221 8 in comparison to three NR sequences. For the genotype 3, no mutations wer e found in the region homologous to 1b-ISDR, but 4 of 5 LTR and RR patients had a mutation T-2161 to A or V versus 0 of 3 NR patients. A close correla tion was found between arginin in position 22 18 in ISDR, the presence of I L-NS 5A Ab, and the response to IFN therapy for genotype Ib, but this assoc iation did not predict a long-term response. For genotype 3, a potential IS D mutation could be located at the codon 2161.