Routine genetic sequencing of the virus showed it looked like no other sample of AIDS virus and it was eventually compared to a gorilla simian immunodeficiency virus, itself only discovered in 2006.

The primate version of the virus that causes AIDS is called simian immunodeficiency virus (SIV), but most apes and monkeys that are infected with it show no symptoms of illness.

AIDS is thought to have originated in Africa, where monkeys and apes harbor a virus similar to HIV called SIV (simian immunodeficiency virus).