AP News: updated 1 hour, 55 minutes ago

WASHINGTON - A new strain of the virus that causes AIDS has been discovered in a woman from the African nation of Cameroon.

It differs from the three known strains of human immunodeficiency virus and appears to be closely related to a form of simian virus recently discovered in wild gorillas, researchers report in Monday's edition of the journal Nature Medicine.

The finding "highlights the continuing need to watch closely for the emergence for new HIV variants, particularly in western central Africa," said the researchers, led by Jean-Christophe Plantier of the University of Rouen, France.

The three previously known HIV strains are related to the simian virus that occurs in chimpanzees.

The most likely explanation for the new find is gorilla-to-human transmission, Plantier's team said. But they added they cannot rule out the possibility that the new strain started in chimpanzees and moved into gorillas and then humans, or moved directly from chimpanzees to both gorillas and humans.

The 62-year-old patient tested positive for HIV in 2004, shortly after moving to Paris from Cameroon, according to the researchers. She had lived near Yaounde, the capital of Cameroon, but said she had no contact with apes or bush meat, a name often given to meat from wild animals in tropical countries.

The woman currently shows no signs of AIDS and remains untreated, though she still carries the virus, the researchers said.

How widespread this strain is remains to be determined. Researchers said it could be circulating unnoticed in Cameroon or elsewhere. The virus' rapid replication indicates that it is adapted to human cells, the researchers reported.

Their research was supported by the French Health Watch Institute, the French National Agency for Research on AIDS and Viral Hepatitis and Rouen University Hospital.