Clinical implications of coinfection with a novel DNA virus (TTV) in hepatitis C virus carriers on maintenance hemodialysis.

A novel hepatitis-associated DNA virus, designated as transfusion-transmitted virus (TTV), was identified recently. We investigated the frequency of TTV viremia in hepatitis C virus (HCV) carriers on maintenance hemodialysis to determine whether TTV coinfection has any clinical relevance. The subjects were 50 hemodialysis patients who had been followed over 4 years after diagnosis of HCV infection. Stored serum samples derived from each patient every 12th month after enrollment were subjected to polymerase chain reaction to amplify TTV DNA and HCV RNA. At enrollment, TTV viremia was detected in 24 (48%) HCV-positive patients irrespective of the number of previous blood transfusions and the duration of hemodialysis. The presence of TTV viremia had no relation to serum alanine aminotransferase (ALT) levels, HCV viremic levels or HCV genotypes. After enrollment, HCV infection persisted in all patients over the 4-year follow-up period, whereas spontaneous resolution of TTV infection was observed in 7 (29%) of the 24 TTV viremic cases (annual rate 7.3%, 95% confidence interval [CI] 0.8-25.5%). Evidence for TTV infection was found in 4 (15%) of the 26 TTV nonviremic patients (annual incidence 3.9%, 95% CI 0.1-19. 6%). The relationship between the ALT profile and TTV infection during follow up was not evident. Active TTV coinfection occurs frequently in HCV carriers undergoing hemodialysis but exerts no biochemical or virological influence on the underlying hepatitis C. Lack of disease association and the frequent spontaneous resolution of infection suggest that the clinical significance of TTV infection remains unclear.