Molecular epidemiology of TT virus (TTV) and characterization of two novel TTV genotypes in Indonesia

The prevalence of TT virus (TTV) DNA among 244 healthy individuals in 23 cities on 12 islands in Indonesia was determined by polymerase chain reaction (PCR) with primers derived from the coding region (N22), which can detect TTV DNA of genotypes 1-6. By N22 PCR, TTV DNA was detected in 102 (42%) individuals. The amplified PCR products were molecularly cloned and three clones each were subjected to sequence analysis. Three hundred one (98%) of the 306 TTV clones were classified into genotype 1, 2 or 3, and none into genotypes 4-6. The remaining five clones from two individuals (Kt-08 and Kt-10) on Kutai, Kalimantan Island, differed by > 30% from known TTV isolates of all 21 genotypes and were tentatively classified into genotypes 22 and 23, respectively. Using primers specific for the new TTV genotype 22 or 23, TTV genotype 22 was detected significantly more frequently in Kutai than in the other 22 cities (41% vs. 5%, P < 0.001). TTV genotype 23 was restricted to Kutai (17% vs. 0%, P < 0.001), suggesting the indigenous nature of this genotype. Analysis of two TTV isolates (Kt-08F and Kt-10F) demonstrated the extreme diversity of TTV and the preservation of the genomic organization and transcription profile.