Human T cell leukemia virus type I is resistant to the antiviral effects of APOBEC3

The objective of this study was to investigate whether the anti-retroviral cellular cytidine deaminase, APOBEC3, inhibits the infectivity of human T cell leukemia virus type I (HTLV-I). Sufficient quantities of cell-free HTLV-I virion for infection were obtained by cotransfecting cells with HTLV-I and human or murine APOBEC3 expression vectors along with a plasmid expressing Tax. HTLV-I viruses containing these deaminases were still capable of infecting 293T and MOLT-4 cells. No G-to-A mutations, which are characteristic of cytidine deaminases, were observed in the HTLV-I genome. These results suggest that the enzymatic activity of APOBEC3 may not contribute substantially to antiviral responses to HTLV-I.