Detection rates of TT virus among children who visited a general hospital in Japan.

Recently, genomic DNA of the novel TT virus (TTV) was isolated from patients suffering from posttransfusion hepatitis of unknown etiology. We examined sera from 197 children who visited the Department of Pediatrics at Toyohashi National Hospital. Sera were tested for TTV DNA by seminested polymerase chain reaction (PCR) using a set of primers synthesized according to the published TTV sequence. Ten children were found to be positive for TTV (5.1%). All positive PCR products were directly sequenced in both directions using a fluorescent dye terminator cycle sequencing system. The sequences were compared by a multiple sequence alignment and a phylogenetic tree was constructed. The phylogenetic tree showed that two of the TTV isolates found in the present experiment did not belong to any of the phylogenetic groups previously reported.