Infection-resistant monkeys could be crucial in the fight against HIV

Via Io9, by Alasdair Wilkins.

Sooty mangabeys are a monkey species found on the western coast of central Africa. Their unique immunity to SIV, a relative of HIV, has intrigued medical researchers for decades. Now we know just how their immunity works.

SIV and HIV function in much the same way - the viruses find two molecules on the surface of the cell, which are known as co-receptors. These molecules function much like gates. One of these molecules is CD4, which is found on immune cells known as T cells. The immune response triggered by the appearance of the virus stimulates these T cells, which boost the level of the other co-receptor, CCR5, which in turn facilitates the deadly infection.

But sooty mangabeys are able to avoid that chain of events, thanks to a unique type of T cell called a central memory T cell. When this particular type of T cell responds to the virus, it does so without activating CCR5. This helps the T cells survive the SIV infection, and it's a crucial reason why these monkeys are able to avoid the onset of AIDS. Best of all, central memory T cells are long-lived in the body, and their positioning in the lymph nodes makes them particularly effective in stopping the spread of SIV.

Emory University researcher Mirko Paiardini explains what this means:

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Precursor to HIV Was in Monkeys for Millenia

via The New York Times, by Donald G. McNeil

In a discovery that sheds new light on the history of AIDS, scientists have found evidence that the ancestor to the virus that causes the disease has been in monkeys and apes for at least 32,000 years — not just a few hundred years, as had been previously thought.

That means humans have presumably been exposed many times to S.I.V., the simian immunodeficiency virus, because people have been hunting monkeys for millenniums, risking infection every time they butcher one for food.

And that assumption in turn complicates a question that has bedeviled AIDS scientists for years: What happened in Africa in the early 20th century that let a mild monkey disease move into humans, mutate to become highly transmissible and then explode into one of history’s great killers, one that has claimed 25 million lives so far?

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