There are four known groups of human HIV. The link to gorillas has been traced to two types: (HIV-1 groups O and P. The connection with gorillas is through the relationship between these particular groups of HIV and simian immunodeficiency virus (SIV). SIV is an infection that arises in some African gorillas.
The link to gorillas would seem to confirm theories that HIV-1, the AIDS-causing virus, crossed the species barrier to infect humans. This would seem, from the connections, to have happened at several time points.
The fact that the gorilla-to-human leap may have happened more than once is based on there being four HIV-1 lineages (described as groups M, N, O, and P.) Other research studies suggest that the two other HIV groups – termed M and N – originated from two different chimpanzee communities located in southern Cameroon. Unlike the M and N groups, the O and P groups are connected with gorillas rather than chimpanzees.
Of the different HIV groups it is group M which has been the most significant and has infected the largest group of people (up to 40 million across the globe.) In contrast the N and P groups have been detected in relatively few individuals. With group O the infectivity rates are a little higher — in the region of tens of thousands — but still someway off the prevlance of the M group.
To draw the gorilla connection, researchers examined many fecal samples deposited via western lowland gorillas, eastern lowland gorillas, and mountain gorillas located in Cameroon, Gabon, the Democratic Republic of Congo, and Uganda. Through various laboratory tests the link to western lowland gorillas was made.
The research findings have been reported to the journal Proceedings of the National Academy of Sciences. The research is titled “Origin of the HIV-1 group O epidemic in western lowland gorillas.”
