| Summary: | The Anelloviruses Torque Teno virus (TTV) and TTV-like minivirus (TLMV) are small, circular DNA viruses which infect humans and non-human primates. They are highly prevalent in the general population; however infection is without any apparent pathology. Both viruses are extremely heterogeneous, especially for DNA viruses, and the role of the immune system in controlling the infection has yet to be established. Initial experiments involved establishing prevalence figures for TTV and TLMV as well as SENV D and H, subtypes of TTV implicated in potential transfusion transmitted non A-E hepatitis, in Scottish blood donors. 88% of serum samples were PCR positive for either TTV, TLMV or a heterogeneous mixture of both viruses. The presence of SENV D and H was determined by Southern blot and revealed 0.5% of samples tested were infected with SENV D, 10.9% with SENV H and 1% with both SENV D and SENV H. We compared the titre of both TTV and TLMV in the bone marrow and spleen from 3 groups: HIV negative individuals, HIV positive individuals and HIV positive individuals who had progressed to AIDS, leading to immunosuppression. The AIDS group had higher tires, which were statistically significant compared with both the HIV positive and negative groups for both bone marrow and spleen. TTV/TLMV tires in HIV positive and transplant patients were compared to individuals infected with viruses not known to cause immunosuppression (HCV and HBV) and healthy blood donors. Both the immunosuppressed groups of individuals had titres of TTV/TLMV in serum higher than the other three groups. The suggestion that farm animals were infected with TTV similar to human TTV led to an investigation of TTV/TLMV homologues infecting non-human primates and farm animals. None of the farm animals were shown to be PCR positive. Sequence analysis of the primate samples determined they were infected with viruses which were genetically distinct from human TTV and TLMV.
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