Study looks at the ability of some monkey species to resist developing AIDS

The Tulane National Primate Research Center received a five-year grant of more than $2 million from the National Institute of Allergy and Infectious Diseases to study the ability of some monkey species to resist developing AIDS.

The study seeks to answer the question of how African green monkeys, when infected with SIV (simian immunodeficiency virus, the monkey equivalent of HIV) are resistant to the development of AIDS, compared to humans and other monkeys.

"The host and virus seem to have developed a relationship over time, through evolution, so the infection isn't as harmful to this type of monkey as it is in other monkeys such as the rhesus macaque," says Andrew Lackner, primate center director.

Scientists once thought natural hosts of SIV such as African green monkeys did not become sick with AIDS when infected with the virus, says Ivona Pandrea, principal investigator of the study. However, recent research shows that the natural hosts can progress to AIDS after a prolonged period of SIV infection without symptoms.

"While a rhesus monkey typically develops AIDS two to four years after infection," Pandrea says," and a human may not develop AIDS for five to 10 years after infection, the African monkeys may not develop AIDS for 20 years, if ever."

In previous work in Gabon, Central Africa, Pandrea studied infection in African green monkeys and mandrills. "We discovered that these monkeys harbor high viral loads, but there are very few cases of AIDS in this species, which may occur only after a very long incubation period, that generally exceeds the normal life span of these monkeys, at least in the wild," Pandrea says.

There have been very few studies with these monkeys that scientists call "long-term progressors," Pandrea says. She hopes that her work might help researchers enhance the human immune system so that HIV-positive people might be able to delay the onset of AIDS.