We posit that these novel findings, made possible by the sequencing of full-length HIV-1 env, could provide potentially high-yield targets for downstream investigation of the implications of amino acid identity on the ability of the virus to persist in the CSF microenvironment, potentially via the infection of and enhanced replication in the various subtypes of CNS-resident macrophage and macrophage-type cells or microglia. This evidence concerns the gene ERVW-1 and infection.