Molecular epidemiology of TT virus in Italy and phylogenesis of viral isolates from subjects at different risk for parenteral exposure

The prevalence and genotype distribution of human TT virus (TTV) in Italy w ere analysed in 593 subjects at different risk of parenteral infection who included blood donors, patients with chronic type C hepatitis (HCV), thalas semic patients, patients on haemodialysis, human immunodeficiency virus typ e 1 (HIV-l)-negative intravenous drug users (IVDUs), and HIV-l-infected sub jects (IVDUs, heterosexual contacts and homosexual males). Plasma TTV-DNA w as detected using nested PCR with primers deduced from the N22 region of th e open reading frame 1 (ORF-1) and from the untranslated region (UTR) of th e viral genome. Phylogenetic analysis of the sequences obtained from ORF-1 was also undertaken. A high prevalence of plasma TTV-DNA was observed using the UTR primers, with rates varying from 83-100% in the study groups. Usin g the N22 primers, HIV-1 positive IVDUs and homosexual males, haemodialysed patients and thalassemic patients had a significantly higher TTV prevalenc e (range: 23.0-86.1%) than blood donors, who displayed a high frequency of positivity (10.6%). Sequence analysis of 127 N22-positive isolates revealed that 42.5% were of type 1, 53.5% of type 2, 2.4% of type 3, and that two i solates (1.6%) were closely related to genotypes 1-2 but distinct from the other major genotypes. TTV-2 was significantly more prevalent in patients a t high risk for parenteral infection and in HIV-1 positive homosexuals. In sequential samples from 15 TTV-infected subjects, N22 sequences were detect able persistently in 12 (80.0%) and UTR sequences persisted in all 15 patie nts over a mean period of 29.6 months. This data indicates that TTV is wide spread in Italy in parenterally exposed subjects, and that the infection fr equently persists. (C) 2001 Wiley-Liss, Inc.