Are hepatitis G virus and TT virus involved in cryptogenic chronic liver disease?

Background. Hepatitis G virus can cause chronic infection in man but the role of this agent in chronic liver disease is poorly understood. Little is known about the relation of another newly discovered agent, the TT virus, with chronic liver disease. Aim. To investigate the rate of infection with hepatitis G virus and TT virus in patients with cryptogenic chronic liver disease. Patients. A total of 23 subjects with chronically raised alanine transaminase and a liver biopsy in whom all known causes of liver disease had been excluded, and 40 subjects with hepatitis C virus-related chronic liver disease. Methods. Evaluation of anti-hepatitis G virus by enzyme immunoassay. Hepatitis G virus-PNA by polymerase chain reaction with primers from the 5' NC and NS5a regions. TT virus-DNA by nested polymerase chain reaction with primers from the ORF1 region. Results. Hepatitis G virus-PNA was detected in 4 out of 23 patients with cryptogenic chronic hepatitis and in 6 out of 40 with hepatitis C virus chronic hepatitis [17.4% vs 15% p=ns]. At least one marker of hepatitis G virus infection [hepatitis G virus-PNA and/or anti-hepatitis G virus, mostly mutually exclusive] was present in 6 out of 23 patients with cryptogenic hepatitis and IS out of 40 with hepatitis C virus liver disease (26.1% vs 40% p=ns). TT virus-DNA was present in serum in 3 subjects, I with cryptogenic and 2 with hepatitis C virus-related chronic liver disease. Demographic and clinical features, including stage and grade of liver histology, were comparable between hepatitis G virus-infected and uninfected subjects. Severe liver damage [chronic hepatitis with fibrosis or cirrhosis] were significantly more frequent in subjects with hepatitis C virus liver disease. Conclusions. In Southern Italy, hepatitis G virus infection is widespread among patients with chronic hepatitis, independently of parenteral risk factors. Its frequency in subjects with cryptogenic liver disease parallels that observed in hepatitis C virus chronic liver disease, thus ruling out an aetiologic role of hepatitis G virus. TT virus infection is uncommon in patients with cryptogenic or hepatitis C virus-related liver disease who do not have a history of parenteral exposure.