PPIG and infection: The TRIM5α TFP/Cyp genotype confers resistance to low-dose simian immunodeficiency virus (SIV) SIVsmE660 (46), but not SIVmac239 and SIVmac251, infection (46, 47), while the genotypes TFP/TFP, Q/Q, and Q/Cyp are associated with increased susceptibility to SIVsmE660 infection (48, 49).