Third-generation assays for hepatitis C antibodies: a four-year study of pattern changes in patients with chronic and past infection

Background. Many advances have been made in the sensitivity of assays for h epatitis C virus antibodies (HCV-Ab). Nevertheless, polymerase chain reacti on (PCR) is still the best method to establish if infection has become chro nic. In this study we utilised third-generation assays for HCV-Ab in a four -year follow-up to determine the trend in antibody levels in currently and past infected patients. Methods. Seventy-two multitransfused subjects were enrolled. All the patien ts were reactive at the first test with third-generation screening and conf irmatory assays (ELISA-3 and RIBA-3) for HCV-Ab. They were subsequently ret ested in a follow-up ranging from 41 to 47 months. Viraemia was investigate d with a standardised PCR kit; negative samples were reevaluated with neste d PCR. Differences in antibody trend were calculated with the Wilcoxon sign ed-rank test. Results. No statistical variation in antibody titre was found in the 41 HCV -RNA positive patients, although some of these showed a decrease in anti-c1 00p level. In contrast, anti-c22p, anti-c33c and anti-c100p levels decrease d significantly in the 19 past infected patients. Twelve patients were HCV- RNA negative or intermittently positive with commercial PCR test, and consi stently or intermittently positive in nested PCR: in these patients, antibo dy trend varied. Conclusions. Although resolving hepatitis is associated with a decrease in antibody titre, the trend should be observed for a long period to distingui sh between chronic and past infection. However, the evaluation in a single patient can be unreliable. Since a doubtful response for HCV-RNA is in some cases obtained, further improvements in the diagnosis of chronic HCV infec tion are needed.