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-transmitt ed virus (TTV), was identified recently. We investigated the frequency of T TV viremia in hepatitis C virus (HCV) carriers on maintenance hemodialysis to determine whether TTV coinfection has any clinical relevance. The subjec ts were 50 hemodialysis patients who had been followed over 4 years after d iagnosis of HCV infection. Stored serum samples derived from each patient e very 12th month after enrollment were subjected to polymerase chain reactio n to amplify TTV DNA and HCV RNA. At enrollment, TTV viremia was detected i n 24 (48%) HCV-positive patients irrespective of the number of previous blo od transfusions and the duration of hemodialysis. The presence of TTV virem ia had no relation to serum alanine aminotransferase (ALT) levels, HCV vire mic levels or HCV genotypes. After enrollment, HCV infection persisted in a il patients over the 4-year follow-up period, whereas spontaneous resolutio n of TTV infection was observed in 7 (29%) of the 24 TTV viremic cases (ann ual rate 7.3%, 95% confidence interval [Cl] 0.8-25.5%). Evidence for TTV in fection was found in 4 (15%) of the 26 TTV nonviremic patients (annual inci dence 3.9%, 95% Cl 0.1-19.6%). The relationship between the ALT profile and TTV infection during follow up was not evident. Active TTV coinfection occ urs frequently in HCV carriers undergoing hemodialysis but exerts no bioche mical or virological influence on the underlying hepatitis C. Lack of disea se association and the frequent spontaneous resolution of infection suggest that the clinical significance of TTV infection remains unclear. (C) 1999 Wiley-Liss, Inc.