IFITM Proteins Restrict HIV-1 Infection by Antagonizing the Envelope Glycoprotein

Yu, Jingyou; Li, Minghua; Wilkins, Jordan; Ding, Shilei; Swartz, Talia H.; Esposito, Anthony M.; Zheng, Yi-Min; Freed, Eric O.; Liang, Chen; Chen, Benjamin K.; Liu, Shan-Lu

The interferon-induced transmembrane (IFITM) proteins have been recently shown to restrict HIV-1 and other viruses. Here we provide evidence that IFITM proteins, particularly IFITM2 and IFITM3, specifically antagonize the HIV-1 envelope glycoprotein (Env), thereby inhibiting viral infection. IFITM proteins interact with HIV-1 Env in viral producer cells, leading to impaired Env processing and virion incorporation. Notably, the level of IFITM incorporation into HIV-1 virions does not strictly correlate with the extent of inhibition. Prolonged passage of HIV-1 in IFITM-expressing T lymphocytes leads to emergence of Env mutants that overcome IFITM restriction. The ability of IFITMs to inhibit cell-to-cell infection can be extended to HIV-1 primary isolates, HIV-2 and SIVs; however, the extent of inhibition appears to be virus strain-dependent. Overall, our study uncovers a mechanism by which IFITM proteins specifically antagonize HIV-1 Env to restrict HIV-1 infection, and provides insight into the specialized role of IFITMs in HIV infection.