Researchers are shaking up the HIV family tree again. For the first time, investigators have found what looks like a gorilla version of the AIDS virus in a person. They do not know how the woman became infected but suspect that other humans harbor a similar virus. The possibility that gorillas can transmit the virus to humans further underscores the danger of butchering the apes or keeping them as pets, which still occurs in some African communities.
Several studies have shown that the most common form of the human immunodeficiency virus, dubbed HIV-1, likely evolved from a chimpanzee relative, SIVcpz. When investigators reported 3 years ago that they had found a similar SIV, SIVgor, in gorillas living in Cameroon, a genetic analysis suggested that it, too, descended from SIVcpz. Now the finding of SIVgor in a Cameroonian woman who moved to France 5 years ago further complicates the story.
In a paper published online this week in Nature Medicine, virologist Jean-Christophe Plantier of the Université de Rouen in France and colleagues describe how a 62-year-old suffering from fevers and weight loss sought medical care shortly after arriving in Paris. The woman tested positive for HIV antibodies and had suffered some damage to her immune cells but had not developed AIDS. Plantier's lab, however, could not make copies of her virus, a standard diagnostic step in wealthier countries that quantifies how much HIV a person has in the blood. He and his collaborators eventually succeeded by using novel reagents designed to sequence unusual HIV strains. The virus they found was most closely related to SIVgor. "I was very surprised to find SIVgor in the human population," says the paper's senior author, François Simon, a virologist at Hôpital Saint-Louis in Paris.
Plantier says a key implication of the study is that gorillas "could be potential reservoirs of a new HIV-1." Viral transmission between gorillas and humans "could be occurring much more frequently than we think," says David Robertson, a computational biologist at the University of Manchester in the United Kingdom, who performed the evolutionary analysis of the virus. "The fact that we could pick up one in Paris means there must be more people with these types of infections."
Many investigators suspect that the main group of HIV-1 viruses, called M, descended from an SIVcpz that moved into humans several hundred years ago because of butchering chimpanzees or handling live ones. But the woman in Paris reported that she had no contact with any apes and did not eat wild game, so-called bushmeat. She told her doctors that she did have sexual partners in Cameroon after her husband died of a non-AIDS-related illness in 1984, so she could have contracted the virus from another person.
The researcher whose lab discovered SIVgor in Cameroonian gorillas, virologist Martine Peeters of University of Montpellier in France, cautions that the woman's virus could ultimately have come from a chimp that infected gorillas and humans many years ago. "We have so few samples from gorillas that we cannot really say whether it came from gorilla or chimp," says Peeters. She is continuing to analyze feces from gorillas in Cameroon for new SIVgor variants, only four of which have been described to date.
Although the new finding does not have any obvious practical importance for treatment or prevention, it reinforces that even 25 years after researchers proved that HIV causes AIDS, many fundamental mysteries remain about the virus's origin and spread.
)
)
)
)
)
)
)
)
)
