http://www.cnn.com/2003/HEALTH/conditions/06/13/monkeys.aid/index.html

AIDS traced to African monkeys

Friday, June 13, 2003 Posted: 11:54 AM EDT (1554 GMT)

Monkeys may carry further deadly viruses that could cause global epidemics, researchers say. Story Tools Special Report: AIDS

LONDON, England -- An international group of scientists has traced the ancestry of the virus that caused AIDS back to strains found in African monkeys.

Two different monkey virus strains combined in chimpanzees to create the HIV virus which was then passed on to humans, the scientists told the journal Science.

Earlier studies had shown that humans contracted the virus that attacks the immune system from chimps, but were unable to determine where the chimps got the virus from.

More than 25 million people have been killed by the AIDS virus that kills white blood cells and causes the body to become defenceless against infections with an estimated 40 million people living with HIV, according to a report by the U.N. last year.

After analyzing the DNA make-up of the simian immunodeficiency virus (SIV) in African monkeys they found the red-capped mangabeys and spot-nosed guenons carried the strains.

The virus was passed onto chimpanzees when they ate infected monkey meat, believe the scientists from universities in France, America and the UK.

The study was undertaken by scientists from the University of Nottingham, the University of Alabama at Birmingham, Duke University, Tulane University and the University of Montpellier in France.

Troops of chimpanzees -- who are apes -- chase monkeys through forests while others wait in trees to catch the monkeys as they run past. The carcasses are ripped apart and eaten on the spot so blood mixing is possible, one scientist said according to The New York Times.

The new evidence suggests that the viral DNA combined to create a hybrid strain from which HIV can be traced.

How humans contracted the deadly virus remains a mystery although it is believed that it was contracted in the same way as chimps through hunting 'bush meat'.

It is generally believed that a chimpanzee hunter contracted the virus in the early part of the twentieth century by cutting himself while preparing the meat.

The virus then mutated into HIV and was passed through millions of human beings.

"The recombination of these monkey viruses happened in chimpanzees and the chimp transmitted it to humans on at least three occasions," said Frederic Bibollet-Ruche, co-author of the study to The Associated Press.

"The transfer between chimps and humans probably happened before 1930," said Bibollet-Ruche from the University of Alabama, Birmingham.

He believes that monkeys and chimps carry many different strains of SIV viruses that could be spread to humans creating a new world epidemic, reported AP.

The findings show that other primate species can acquire the virus under natural conditions.

Last year French scientist found that one strain of the SIV virus contained a gene that allowed it to pass straight to man from monkeys. The SIV virus does not cause disease in chimps and monkeys.