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 fo r 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 fa ctor VIII concentrates, Elevated ALT levels were observed in patients with HCV RNA and TTV DNA: however, the elevation in TTV DNA was obtained from pa tients co-infected with HCV RNA (62.9%, 22/35). There was no significant di fference in ALT levels between TTV DNA-positive and DNA-negative in patient s without HCV RNA. 85.3% (35/41) of TTV DNA-positive sera in 1990 were agai n positive for TTV DNA in 1995, These findings suggest that many haemophili acs have been infected with TTV. Although TTV infection was not associated with serum ALT elevation, persistent TTV infection may contribute to crypto genic hepatic failure in haemophiliacs.