TT viruses (TTV) of non-human primates and their relationship to the human TTV genotypes

Sera from eight different non-human primate species, in total 216 samples, were analysed for the presence of TT virus (TTV) sequences. A very high incidence of TTV infection was found in sera from both common chimpanzees and pygmy chimpanzees, 48.8% and 66.7%, respectively. Sequence analysis of PCR fragments from two pygmy chimpanzees and seven common chimpanzees resulted in a total of 14 different TTV sequences. Phylogenetic analysis, including human TTV of all known genotypes, revealed that: (i) TTV from pygmy chimpanzees are closely related to viruses from human genotypes 2 and 3; (ii) TTV sequences obtained from common chimpanzees cluster together with human TTV genotypes 5 and 6, the latter only at the protein level; (iii) TTV from the common chimpanzee subspecies Pan troglodytes verus and Pan troglodytes schweinfurthii cluster together, suggesting an ancient host-pathogen relationship before subspeciation 1.6 million years ago; and (iv) TTV of common and pygmy chimpanzees may have been acquired by these animals in different zoonotic events not longer than 2.5 million years ago.