Clinical implications of TT virus superinfection in patients with chronic hepatitis C

OBJECTIVE: TT virus (TTV) has been identified as a candidate agent of non-A -E hepatitis virus. We investigated superinfection of TTV in patients with chronic hepatitis C and studied the susceptibility to interferon (IFN) trea tment and its association with liver disease caused by hepatitis C virus (H CV). METHODS: TTV DNA was examined using the seminested polymerase chain reactio n (PCR), and its virus level was measured by the real-time fluorometric PCR . RESULTS: TTV DNA was detected in 20 of 102 (19.6%) patients examined. There was no significant difference in the alanine aminotransferase (ALT) level between patients with or without TTV DNA. Quantitative analysis of HCV RNA and TTV DNA revealed no correlation between virus levels in HCV/TTV-coinfec ted patients. Both TTV and HCV were sensitive to IFN therapy. Complete resp onse to IFN with a sustained loss of viremia for 24 wk after completion of IFN treatment was found in 11 of 20 (55%) patients with respect to TTV DNA and in five of 20 (25%) patients with respect to HCV RNA. The mean pretreat ment HCV RNA level was significantly lower in the complete-response cases t han in the no-response cases, but there was no significant difference in th e pretreatment TTV DNA levels between them. ALT normalization resulting fro m IFN therapy was not attributable to the eradication of TTV DNA but was at tributable to that of HCV RNA. Superinfection by TTV did not influence the effect of IFN against HCV. No specific TTV genotype correlating with IFN se nsitivity was found. CONCLUSIONS: These results suggest that TTV infection stands independent of HCV infection, with no influence on liver injury as a result of HCV infect ion. (C) 2000 by Am. Coll. of Gastroenterology).