Comparative requirements for the restriction of retrovirus infection by TRIM5α and TRIMCyp

The restriction factors, TRIM5α in most primates and TRIMCyp in owl monkeys, block infection of various retroviruses soon after virus entry into the host cell. Rhesus monkey TRIM5α (TRIM5αrh) inhibits human immunodeficiency virus (HIV-1) and feline immunodeficiency virus (FIV) more potently than human TRIM5α (TRIM5αhu). TRIMCyp restricts infection of HIV-1, simian immunodeficiency virus of African green monkeys (SIVagm) and FIV. Early after infection, TRIMCyp, like TRIM5αrh and TRIM5αhu, decreased the amount of particulate viral capsid in the cytosol of infected cells. The requirements for the TRIMCyp and TRIM5α domains in restricting different retroviruses were investigated. Potent restriction of FIV by TRIMCyp occurred in the complete absence of RING and B-box 2 domains; by contrast, efficient FIV restriction by TRIM5αrh required these domains. Variable region 1 of the TRIM5αrh B30.2 domain contributed to the potency of HIV-1, FIV and equine infectious anemia virus restriction. Thus, although differences exist in the requirements of TRIMCyp and TRIM5α for RING/B-box 2 domains, both restriction factors exhibit mechanistic similarities.