[Current developments in the diagnosis of hepatitis C].

Abstract

Since the discovery of hepatitis C virus five years ago eight complete isolates and a large number of partial isolates have been sequenced. By comparing sequences, six HCV types can be differentiated which show more than 35% divergency in the NS5 proteins. The course of hepatitis C and the response rate after interferon therapy may be dependent on the HCV type. Serological tests for the diagnosis of acute and chronic hepatitis C have been improved, so that more than 90% of patients seroconvert at the peak of transaminases during acute infection; however in single cases, seroconversion can last up to nine months after onset of disease. Antibodies which can be detected in the acute and chronic phase of hepatitis C are directed against structural and nonstructural proteins. Most recently, also antibodies enveloping proteins E1 and E2 have been identified. These antibodies obviously do not seem to neutralize the virus. In patients with acute hepatitis C and complete recovery antibodies may persist up to ten years after onset of disease. At present there is no marker for past infection or immunity to HCV. Chronicity of hepatitis C and infectivity of patients can only be shown by detection of viral RNA using RT-PCR. Indications to perform PCR are patients prior to and after interferon therapy, hemodialysis patients, patients undergoing immunosuppression, new-born babies of mothers with chronic hepatitis C and patients with acute hepatitis C who are negative for antibodies.