Origins of 2 AIDS strains traced to gorillas

Two of four strains of the virus that can cause AIDS come from gorillas in southwestern Cameroon, an international team of scientists reported in studies published on Monday in the United States.

The new information means that researchers now know the origins of all strains of HIV that occur in people.

HIV (HIV-1) has at least four strains. Known as groups M, N, O and P, each one had its own origin from ape to man on at least four separate occasions.