The New York Times - August 5, 2009
Lawrence K. Altman

It is thought to be likely that this is the first time scientists have documented the jump of a simian immunodeficiency virus to humans from a gorilla. All three other known strains of the human immunodeficiency virus, H.I.V.-1, have been linked to chimpanzees. But genetic tests showed that the new virus was closely related to a recently recognized gorilla virus.

The most likely explanation for the new virus's emergence is gorilla-to-human transmission, probably a result of humans slaughtering apes or handling or eating their meat.

But the scientists said they could not dismiss the possibility that the chimpanzee virus linked to H.I.V.-1 was transmitted to gorillas and then to humans, or was directly transmitted to humans and then to gorillas.

The new virus strain was isolated in 2004 from a 62-year-old woman upon her arrival in Paris from Cameroon in West Africa. She has not been treated for AIDS and has no signs of the syndrome, the scientists said.

The woman had lost weight in 2003 and had been ill with a fever a number of times, the scientists said in reporting the discovery, in the Aug. 2 issue of the journal Nature Medicine.

Her husband died in 1984 from complications of a stroke. It is not known if he was infected with H.I.V. The woman had six children, all born before 1980, a year before doctors first recognized AIDS; two of the children died of noninfectious causes, and none of the surviving children have H.I.V.

The authors of the report said they presumed that she had been infected through sex. The woman told her doctors that she had sexual partners in Cameroon after her husband's death, but there was no information about whether any were infected -- or, if they were, how they had contracted the virus.

The amount of virus in her blood is high, reported the French and British scientific team, which was led by Jean-Christophe Plantier of the University of Rouen in France. But the number of CD-4 blood cells, a key laboratory measure of the progression of AIDS, is stable at about 300 per cubic millimeter.

The scientists suspect that there are additional undetected cases because the patient lived in a semiurban area of Yaounde, the capital of Cameroon, and she said she had no contact with apes or their meat. More studies are needed to determine how often the new virus infects people.

The discovery was part of continued monitoring for new viruses. The goal is to identify a simian or other virus before it can cause another epidemic like AIDS, which has affected more than 33 million people worldwide.

The new virus may escape detection by standard blood and laboratory tests for H.I.V.-1. New testing methods developed in recent years have allowed scientists to detect subtypes of H.I.V.-1. The three others are known as H.I.V.-1 Groups M, N and O. Dr. Plantier's team calls the new one H.I.V.-1 Group P.
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