TT virus (TTV) genotypes in native and non-native prostitutes of Irian Jaya, Indonesia: implication for non-occupational transmission

We investigated prostitutes in Irian Jaya, an Indonesian territory of New Guinea, to know whether TT virus (TTV) is sexually transmitted and what genotypes of TTV exist there. An ORF2 region of the TTV genome was analyzed for 44 isolates from prostitutes (19 were Irian Jaya natives but 25 were immigrants from Java or other islands of Indonesia) and 26 isolates from women of child-bearing age in Surabaya as a control. The WX(7)HX(3)CX(1)CX(5)H motif sequence of the ORF2 was compared across the 70 Indonesian isolates with a reference of 47 Japanese isolates (filed in databases) and the prototype TTV isolate TA278. A total of 77 different sequences were generated from the comparison, but a phylogenetic analysis suggested that they could be divided into three categories: group A, group B and others (the third group was highly diverse). Interestingly, most of the Indonesian isolates belonged to group B (74%): this rate was considerably higher than that observed previously in Japanese isolates. Group B isolates were further compared for the N-terminal 95 amino acids of the ORF2, with a result that the natives of Irian Jaya had a different pattern of genotype distribution from other groups. In particular, 9 out of 19 isolates from the Irian Jaya-natives were co-classified under a distinct branch, to which none of the other Indonesian and Japanese isolates belonged. Our data indicate that TTV genotypes reflect the birth place of the infected prostitutes rather than their work environment, and thus suggest that an infection is more likely during the early period of life than through sexual transmission. In addition, the presence of an Irian Jaya-specific genotype is intriguing from an anthropological and viral evolutionary point of view, because Irian Jaya has been isolated from contact with other areas for a long time.