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

Abstract

A part of the hepatitis C virus (HCV) nonstructural protein 5A (NS5A) amino acid sequence, designated as an interferon (IFN)-sensitive determining region (ISDR), has been shown to be correlated with a response to IFN in Japanese 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 IL3R. Serum samples from 52 patients infected by HCV genotypes 1, 2, and 3 were analyzed before and after treatment. The patients were classified as nonresponders (NRs), responder-relapsers (RRs), or long-term responders (LTRs). We amplified the NS5A region for 42 patients using polymerase chain reaction (PCR), and these amplicons were sequenced directly. The 10 remaining patients were analyzed using PCR with mutation-specific primers. No correlation was found between the IL3R sequence of the HCV strains and the presence of the IL-NS5A Ab for all genotypes. However, for the subtype 1b, only 2 of 11 NR patients 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 2216-2218 in comparison to three NR sequences. For the genotype 3, no mutations were 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 correlation was found between arginin in position 2218 in ISDR, the presence of IL-NS5A Ab, and the response to IFN therapy for genotype 1b, but this association did not predict a long-term response. For genotype 3, a potential ISD mutation could be located at the codon 2161. (HEPATOLOGY 1998;28:1674-1679.)Hepatitis C virus (HCV) is the main cause of non-A, non-B hepatitis. 1 The HCV genome is a single strand of positive RNA composed of a region coding for structural proteins (core and glycoproteins E1, E2, and p7) in its first terminal third and region coding for nonstructural proteins (NS2, NS3, NS4A/B, and NS5A/B) in the remaining part. HCV infection can be diagnosed by serological methods and 5Ј-untranslated region polymerase chain reaction (PCR). Third-generation confirmatory assays have been developed to detect antibodies (Abs) against structural and nonstructural antigens as shown by the INNOLIA HCV Ab III test (Innogenetics, Antwerp, Belgium), which detects nonstructural protein 5A Abs (IL-NS5A Ab).Interferon (IFN) has some efficacy on chronic hepatitis C, but relapse is common when treatment is discontinued. 2,3 We have shown previously 4 that sensitivity to IFN is closely associated with the presence of IL-NS5A Ab. In this previous study, 95% of long-term responders (LTRs; 20 of 21) had IL-NS5A Ab versus 13% of nonresponders (NRs; 3 of 23). Concurrent with this work, several studies in Jap...

Mutations within the E2 and NS5A protein in patients infected with hepatitis C virus type 3a and correlation with treatment response

“…18 Comparison of the HCV-3a prototypes HCV-K3a and NZL1 at position 2161 shows threonine †Carboxyterminal part of the E2 region, including PePHD and 5Ј-, 3Ј-flanking regions; codon 638-704 according to NZL1. 26 ‡PePHD 20 ; codon 665-676 according to NZL1.…”

“…[14][15][16][17] In patients infected with HCV genotype 3a isolates, no association between the number of mutations within the ISDR and treatment response was observed. 13,17,18 A possible association of treatment response and mutations within the complete PKR-binding domain in HCV-3a-infected patients has yet not been investigated. Moreover, upstream from the PKR-binding domain a single mutation (T2161A or V, according to HCV-3a prototype NZL1) has been suggested to be correlated with virological response.…”

“…Moreover, upstream from the PKR-binding domain a single mutation (T2161A or V, according to HCV-3a prototype NZL1) has been suggested to be correlated with virological response. 18 Recently, an interaction of another HCV protein with PKR/eIF2␣ pathway was shown. HCV envelope 2 (E2) protein of HCV-1a/b isolates contains a PKR-eIF2␣ phosphorylation homology domain (PePHD) between amino acid residue 659 and 670 according to HCV-J.…”

Mutations in nonstructural protein 5A gene and response to interferon in hepatitis C virus genotype 2 infection

“…18 However, there is substantial discrepancy in the significance of the NS5A structure on interferon efficacy among Western countries. Some studies did not find any correlation between NS5A structures and interferon effect, [19][20][21][22][23][24][25] while other studies did. 26,27 In addition, in HCV genotype 1a, [21][22][23] 2c, 23 or 3a, 19,23,27 no clear association has been found.…”

Viral Factors Associated with Response to Antiviral Therapy for Chronic Hepatitis C Virus Infection

“…However, mutations in the region corresponding to the ISDR of G1b (2126-2228) was reported to be associated with outcome of therapy in HCV G2a, and more than two mutations in ISDR were associated with good response to PEG-IFN plus RBV [39]. Although there was a report on a particular aa substitutions in ISDR in relation to the response to IFN [40], data were unclear.…”