[Susceptibility of TT virus to interferon therapy].

A novel single stranded DNA virus, TT virus, associated with posttransfusion hepatitis was identified. The impact of the virus on development of chronic liver diseases and the susceptibility of the virus to interferon therapy has not been investigated. We retrospectively analyzed blood samples from 16 patients infected with both hepatitis C virus and TT virus who were treated by interferon. TT virus DNA was detected by nested polymerase chain reaction before, during and after interferon. Eight of these 16 patients became negative for TT virus DNA after such therapy but the virus re-appeared in one patient after cessation of therapy. All nine patients in whom interferon eliminated HCV exhibited normalization of alanine aminotransferase activity irrespective of persistence of TTV. In contrast, five of the seven patients who showed persistence of HCV after interferon had high levels of alanine aminotransferase (P = 0.034). These results suggest that TTV is sensitive to interferon and eradicated in a half of treated patients, but persists without liver injury for a long period in some patients.