Prevalence and partial characterization of genotypes of the human TT virus infecting Portuguese individuals

The prevalence and genotype distribution of human TT viruses (TTV) were analyzed in 312 Portuguese individuals. Detection of TTV DNA was carried out by polymerase chain reaction (PCR) through the combined use of N22 and UTR-specific primers and revealed a prevalence of infection of 74%. Detection of TTV DNA was not statistically associated to the use of intravenous drugs, infection with HBV, HCV, HIV-1, HIV-1 viral load or CD4 cell count (in HIV-1 infected individuals). Our data suggest that, in the population studied, the prevalence of TTV infection does not seem to be related to intravenous viral transmission. Phylogenetic analysis of 49 plasmid clones harboring N22-specific sequences revealed the circulation of genotypes: 1 (27%, subtype G1a and G1b), 2 (51%, subtype G2b and G2c) and 4 (22%), as well as multiple genotype infections (G1b-G2b and G1a-G4). To our knowledge, this is the first report of TTV detection and partial characterization of TTV genetic variants in Portuguese individuals. Our results show that TTV infection is widespread in Portugal as in other parts of the world.