This phenomenon was defined in studies of viral Env and antibody coevolution in chronic HIV-1 infection [6,8] and supports the notion that Env variants, during viral infection with mutations that confer enhanced neutralization by members of an antibody lineage, may serve as immunogens to mature such lineages to enhanced neutralization potency and/or breadth against different HIV-1 strains [6]. Here, ERVW-1 is linked to viral infectious disease.