A woman who tested positive for HIV has been found to be carrying a new strain of the virus which is thought to have originally been passed to humans by gorillas.
The new strain was identified in a 62-year-old woman who moved to Paris after living in Yaounde, the capital of Cameroon. Three other strains of HIV-1 have previously been identified and are all thought to have derived from a similar virus carried by chimpanzees.
The discovery of the new virus dramatically strengthens evidence that HIV was transmitted to humans from both chimpanzees and gorillas. Researchers from the Anglo-French team that identified the fourth type of HIV-1 said it more closely related to the recently discovered gorilla version of simian immunodeficiency virus, SIVgor, than the varieties associated with chimpanzees.
It is almost certain that other people have the new variety of HIV-1 as the virus appears well-adapted to the human system and the woman it was found in told researchers she'd had no contact with live gorillas or bushmeat. However, scientists are uncertain how widespread the variety is and have yet to establish how dangerous it is. The Cameroonian woman tested HIV positive in 2004, but has yet to show any signs of AIDS.
The researchers reported their findings in the journal Nature Medicine and concluded: "The discovery of this novel HIV-1 lineage highlights the continuing need to watch closely for the emergence of new HIV variants."