ERVW-1 and infection: IFITM3 restricts HIV-1 infections at different stages of the HIV-1 replicative cycle by blocking viral entry through IFITM3 incorporation on virions and direct interactions between IFITM3 and HIV-1 env (Yu et al., 2015; Drouin et al., 2021), and at later stages of infection when IFITM3 blocks viral protein synthesis (Lee et al., 2018).