ERVW-1 and infection: The early analysis of the immune correlates of infection risk in the RV144 vaccinees demonstrated that IgG antibodies binding to the variable regions 1 and 2 (V1V2) of the HIV envelope (Env) correlated inversely with the risk of HIV-1 acquisition, while high levels of plasma IgA antibodies against Env correlated with an increased risk of HIV infection [13].