Improved detection systems for TT virus reveal high prevalence in humans, non-human primates and farm animals

TT virus is a newly described agent infecting humans. Initially isolated from a patient (initials T.T.) with unexplained hepatitis, the virus has since been found in both normal and diseased individuals. In the present study, we utilized genomic-length sequences from distinct genotypes of TT virus to design PCR-based assays using conserved oligonucleotide primers from three independent regions of the virus genome. Each of the three assays was found to be superior to the PCR-based assays previously published. The most sensitive of the new assays was utilized to demonstrate the prevalence of TT virus to be at least 34–1 % in volunteer blood donors, 39–6 % in commercial blood donors, 59–6 % in non-A–GB hepatitis cases, 81–7 % in injectable drug users and 95–9 % in haemophiliacs. In an attempt to identify a possible source of human infection, we found TT viru