Scientists have finally identified the secret that helps Sooty mangabeys, a type of African monkey, survive infection by SIV, a relative of HIV, and not succumb to AIDS.
They found sooty mangabeys's immune cells resist infection by closing the gates that SIV and HIV use to get into the cell- findings, which may lead to strategies to help HIV-infected individuals cope better with infection.
"We have shown sooty mangabeys can prevent SIV from infecting a very important part of the immune system," said first author Mirko Paiardini, PhD, senior research scientist at Yerkes National Primate Research Center, Emory University.
"This protection from infection comes from reducing the levels on the cell surface of a molecule that SIV uses to enter the cell," he explained.
To infect a cell, HIV and SIV need to find two molecules on the cell's surface. Scientists call these molecules co-receptors, and they can be thought of as gates.
One of the co-receptors is CD4, which appears on immune cells called T cells. The other is called CCR5. Stimulating a T cell usually increases the level of CCR5, facilitating infection.
Paiardini and his colleagues found that in sooty mangabeys, a type of T cell called a central memory T cell doesn't turn on CCR5. This means that even when a sooty mangabey is infected with SIV, some T cells can mostly avoid being killed by the virus.
The results are published online in the journal Nature Medicine.