Multiple infection of TT virus (TTV) with different genotypes in Japanese hemophiliacs

To clarify the persistent TT virus (TTV) infection, we studied a possibility of multiple TTV infection by genotype analysis of isolated TTV obtained from seven Japanese hemophiliacs. The nucleotide sequences including 222 bp in the open reading frame 1 (ORF1) region of 10 TTV isolates from each patient were analyzed and classified into various TTV genotypes such as G1 to G6 by phylogenetic analysis using a N-J method. Multiple TTV genotypes were observed in all the hemophiliacs: three different TTV genotypes were found in three patients, whereas four different TTV genotypes were observed in the other three patients. The remaining patient was also infected with TTV of five different genotypes. Moreover, new TTV genotypes were found in these seven patients and tentatively designated as G7. The present findings indicate that multiple TTV infection with different TTV genotypes has occurred in Japanese hemophiliacs. They also provide valuable information to understand persistent TTV infection.