Prevalence and persistence of a novel DNA TT virus (TTV) infection in Japanese haemophiliacs

To clarify the clinical implication of a newly discovered 'TT virus (TTV)', we assayed TTV DNA in sera from 50 haemophiliacs by a seminested-PCR. TTV DNA was detected in 75% (35/50), which was a much higher prevalence than for HBV (HBc-Ab), HCV RNA, or HGV RNA. In particular, TTV DNA was found in 44.4% (4/8) of patients who had been treated only with virally inactivated factor VIII concentrates. Elevated ALT levels were observed in patients with HCV RNA and TTV DNA; however, the elevation in TTV DNA was obtained from patients co-infected with HCV RNA (62.9%, 22/35). There was no significant difference in ALT levels between TTV DNA-positive and DNA-negative in patients without HCV RNA. 85.3% (35/41) of TTV DNA-positive sera in 1990 were again positive for TTV DNA in 1995. These findings suggest that many haemophiliacs have been infected with TTV. Although TTV infection was not associated with serum ALT elevation, persistent TTV infection may contribute to cryptogenic hepatic failure in haemophiliacs.