A trans-national group of researchers have pinpointed the source for the HIV virus that causes AIDS, in a population of chimpanzees in Cameroon. The find is likely to accelerate research into possible vaccines by studying how the chimpanzee physiology deals with the illness. The team, bringing together researchers from the Cameroon, France, the UK and US, located a chimpanzee version of the Simian Immunodeficiency Virus (SIV) in 29 to 35 per cent of the adult chimpanzee population, but without exhibiting any symptoms. This could present important avenues for further research. The SIV and HIV viruses are very closely related, and the team studied faecal samples to locate SIV antibodies and nucleic acids. They found that HIV virus samples could be traced to specific chimpanzee communities along the border between Cameroon and the modern-day Democratic Republic of Congo (DRC). The discovery ends more than 10 years of research into the origins of HIV. The team believe that the virus may have first crossed-over to humans as long ago as the 1920s. The disease spread slowly and unrecognised until it reached Kinshasa in the modern-day DRC, where the first human epidemic began in around 1930. The disease would not have then been recognised, as people will have died, as is still the case with HIV/AIDS, from a variety of distinct symptoms. The researchers restricted their search to the south side of the Sanaga river in south-east Cameroon. Only chimpanzees on the south side were found to carry the SIV virus. 'For us, this is really the last piece of the puzzle,' said Paul Sharp, professor of genetics at Nottingham University told the Guardian newspaper. 'This is where it probably all started. We've got these viruses in south-east Cameroon, which are so close to HIV, and it's difficult to envisage there could be any which could be closer.' The Nottingham team used the Chimpanzee faecal samples to find SIV virus particles and isolate them, and compare them to HIV samples. Because the virus types are so similar, and because humans and chimpanzees are also so similar, researchers will now investigate why HIV is so debilitating for humans, yet SIV is apparently harmless for chimpanzees. SIV probably crossed from chimpanzees to humans through blood contact with hunters. Researchers have located further sources of SIV in monkeys, and there is some debate as to whether the monkeys could have been a further point of contact with humans, but as chimpanzees often hunt monkeys, the chimpanzees remain the most likely contact point. In the short term, information campaigns can run in areas where humans come into regular contact with chimpanzee populations, so that more unintentional infections can be avoided - particularly those cultures keen on eating 'bushmeat'. In the longer term, the discovery will open new doors in the search for an effective HIV vaccine. When researchers know how the SIV virus works in the chimpanzee physiology without effect, we may learn how to render HIV useless in humans.
Congo, Cameroon, France, United States