SHIV AD8-EO was derived by five serial-macaque passages followed by further adaption in macaque PBMCs [8] while SHIV Q23AE was generated from a HIV-1 Env from early in infection and then modified with a single amino acid substitution (A204E) to allow the Env to use macaque CD4 for entry [42]. The gene discussed is ERVW-1; the disease is infection.