Pattern of HCV antibodies with special reference to NS5A reactivity in HCV-infected patients: relation to viral genotype, cryoglobulinemia and response to interferon

Background/Aims: We aimed to compare the anti-hepatitis C virus reactivity in confirmatory assays (RIBA 3.0 ©Ortho Diagnostic and INNO-LIA HCV Ab III ©Innogenetics) among patients infected with different hepatitis C virus genotypes, with or without cryolobulinemia, and in patients treated with interferon. Methods: One hundred and three patients followed in our hepatogastroenterology unit were included in the study and compared to 320 consecutive patients tested using RIBA 3.0. Seventy-nine of the 103 patients were treated with interferon. Long-term responders to interferon were defined as having normal alanine aminotransferase levels and being HCV RNA negative 6 months after the end of treatment. Initial responders were defined as having normal alanine aminotransferase levels at the end of interferon therapy but abnormal alanine aminotransferase levels and/or detectable HCV RNA during the following 6 months. Non-responders were defined as still having elevated alanine aminotransferase during and after interferon. Serological tests (RIBA and INNO-LIA) were performed according to the manufacturersʹ instructions. HCV RNA was detected by nested polymerase chain reaction. Hepatitis C virus genotype was determined by using a Line Probe Assay (©Innogenetics). Results: There was no significant difference in the pattern of hepatitis C virus reactivity according to the hepatitis C virus genotype or presence of cryolobulinemia. Twenty-three patients were classified as non-responders, 35 as initial responders, 21 as long-term responders. NS5 reactivity was significantly different (p<0.01) between these three groups: 34% of non-responders ( ) had RIBA 3.0 NS5 reactivity and 13% ( ) were reactive in the INNO-LIA III. Almost all long-term responders (95%) had NS5 reactivity by both RIBA 3.0 and INNO-LIA III. Conclusion: We conclude that patients who respond to interferon have stronger reactivity against NS5 antigens than non-responders. Molecule changes in the NS5A region may be responsible for such differences, as recently suggested.