ERVW-1 and HIV-1 infection: Although HIV-1 infection and Env immunization elicit an abundant production of Env-directed antibodies, many of them cannot completely suppress virus replication in infected hosts due to the effective strategies of HIV-1's immune evasion, including the rapid genetic variation,20,21 the glycan shield,22–24 and the conformational masking,10 all of which enable HIV-1 to escape neutralizing antibodies.