TRIM5 and HIV-1 infection: Successful simian tropic (st) HIV-1 infection of pig-tailed macaques (M. nemestrina) [49], which express a TRIM5-cyclophilin fusion (TRIM-Cyp) that is unable to restrict HIV-1 [50]–[53], demonstrates that the HIV-1 host-range can include macaques when APOBEC3- and TRIM5-imposed restrictions are absent.