TT virus infection in patients with hepatitis C: Frequency, persistence, and sequence heterogeneity

TT virus (TTV) was recently identified in the serum of a patient with hepat itis. The role of TTV in liver disease has not been established. Three poly merase chain reaction (PCR) protocols were used to detect TTV DNA in sera o f persons infected with hepatitis C virus (HCV) and in blood donors. Sera f rom 11.5% of HCV-infected patients and 7.7% of blood donors were positive b y protocols 1 or 2. In contrast, 48.7% and 57.7% of sera, respectively, wer e positive when tested by protocol 3, There was no difference in the severi ty of hepatitis in persons coinfected with TTV and HCV when compared with t hose infected with HCV alone, regardless of which TTV PCR protocol was used . TTV DNA persisted in serum samples taken up to 6 years apart in individua l patients. Sequence analysis indicated that most viral sequences were dist inct between patients, and there was evidence of genetic heterogeneity and viral evolution within individuals.