EULALEE THOMPSON
CONSPIRACY THEORIES abound - a polio vaccine mishap, biological warfare by the Russians, a plot to wipe out black people and so on - all to explain the surreptitious appearance of the human immunodeficiency virus (HIV), the virus that causes AIDS, in the twentieth century.
Now, last week, an international team of researchers from the universities of Nottingham, Montpellier and Alabama say that they have found the origin of HIV - you guessed it, wild chimpanzees and not just any wild chimp, but African chimps, specifically those living in southern Cameroon.
Researchers have been toying with the chimpanzee/monkey theory for years. It was speculated in the early 1980s (by Robert Gallo) that the AIDS virus crossed species from an African green monkey. That theory didn't hold up, but Simian Immunodeficiency Viruses (SIVs) were identified as closely related to HIV.
The findings of this latest study are to be published in Science magazine but the British Broadcasting Corporation (BBC) reports that the scientists have identified a natural reservoir of Simian Immunodeficiency Virus from chimps (SIVcpz).
During this 10-year study to identify the source of HIV, many laboratory tests were done, including of chimpanzee faeces collected from remote African jungle areas. In about 35 per cent of chimpanzees in some groups, the scientists found SIVcpz specific antibodies and genetic information linked to HIV. In the final analysis, the scientists found an extremely close genetic relationship between some samples and strains of HIV. Chimpanzees in south-east Cameroon were found to have the viruses most similar to HIV linked to the worldwide pandemic.
The scientists still have not been able to explain that SIVcpz has not been found to cause AIDS-like symptoms in chimpanzees, though they are genetically similar to human beings.
Is this the once-and-for-all answer to the origin of HIV? Publication of the full study should give more information and hopefully generate more international discussion.
POLIO THEORY DISCREDITED
The polio-vaccine-gone-wrong theory was thrown out early. Some scientists had speculated that an experimental polio vaccine used in Central Africa in the 1950s resulted in the spread of HIV in the general population. The World Health Organisation (WHO, 2000) refuted these arguments by scientists and others (specifically Edward Hooper), suggesting that the polio vaccine was a channel through which HIV crossed species.
The WHO said that genetic sequencing suggests that HIV first entered the human population around 1930, well before the vaccine trials of the 1950s; experimental polio vaccine (in storage since 1950s) tested negative for HIV, SIV and chimpanzee DNA and that processes used to manufacture the vaccine do not permit for contamination with HIV or SIV.
WHY STUDY HIV ORIGIN?
Scientists generally believe that studying the origin of HIV presents more opportunities to develop more effective treatments or even a HIV vaccine. Understanding the HIV origins may also assist public health specialists and scientists to deal with (maybe prevent) future pandemics.
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