When PTM were infected with SIVmac239ΔGY containing R722G alone, 2 of 3 animals progressed to AIDS with high viral loads that were associated with the appearance of additional changes in the Env CD, either 1) a new ΔQTH deletion generating a YFQL (Fig 9 and S7E Fig), or 2) 3 substitutions (T735I, Q739R, and P744L) that evolved to a consensus sequence (Fig 9 and S6F Fig). Here, ERVW-1 is linked to AIDS.