The entire nucleotide sequences of two distinct TT virus (TTV) isolates (TJN01 and TJN02) remotely related to the original TTV isolates

TT virus (TTV) has a wide range of sequence divergence by which it is class ified into at least 16 genotypes. A TTV isolate of genotype 12 (TJN01) and another of genotype 13 (TJN02) were sequenced in the entire genome, and com pared with the reported TTV isolates. TJN01 and TJN02 had genomic lengths o f 3787 and 3794 nucleotides (nt), respectively, which were shorter by 66 an d 59 nt than the prototype TTV isolate of genotype 1 (TA278). TJN01 and TJN 02 shared the nucleotide sequence with TA278 merely in 53.9% and 55.2%, res pectively. They possessed two major open reading frames (ORFs) and the nonc oding region with a GC-rich region forming stem-loop structures, which are characteristic of TTV. However, their amino acid sequences in ORF1 were sim ilar to that of TA278 in only 35.4 and 34.0%, respectively; TJN01 was 45.4% similar to TJN02. Comparison with TTV isolates of the same genotype identi fied hypervariable regions in ORF1 of TJN01 and TJN02, as in the prototype TTV of genotype 1. However, quasispecies were barely observed in them. Furt hermore, sequences of hypervariable regions scarcely changed during 2-5.5 y ears in both TJN01 and TJN02. These results indicate that TTV of genotypes 12 and 13 are much different from the prototype TTV of genotype 1.