Retroviral Restriction Factors TRIM5α: Therapeutic Strategy to Inhibit HIV-1 Replication

Tripartite motif protein 5-alpha (TRIM5 alpha) is a cytoplasmic protein that efficiently recognizes the incoming capsid (CA) protein of retroviruses and potently inhibits virus infection in a species-specific manner. Through directly recognizing and interacting with HIV CA, TRIM5 alpha is capable of disrupting the ordered process of viral uncoating, eventually interfering with HIV-1 reverse transcription and virus replication. TRIM5 alpha protein contains four domains: RING domain, B-box 2 domain, coiled-coil domain, and B30.2 domain (SPRY) domain. All of the domains are necessary for efficient retrovirus restriction and the B30.2 domain has been shown to be the determinant of the specificity of restriction. Species-specific innate resistance against viral infections offers novel avenues for antiviral therapeutics. Various mutants of TRIM5 alpha have been described which differently affect the HIV-1 reverse transcription process. This makes the establishment of new and improved models for HIV replication and AIDS pathogenesis by monitoring endogenous TRIM5 alpha an attractive approach. TRIM5 alpha-mediated restriction is modulated by the host protein Cyclophilin A (Cyp A) which could effectively interact with the CA of HIV-1. Here we will review the structure and roles of TRIM5 alpha protein, the interaction between Cyp A and TRIM5 alpha, as well as gene therapy strategies associated with TRIM5 alpha to inhibit HIV-1 infection.