Origin Of Human Immunodeficiency Virus Type 1 example essay topic

The origin of human immunodeficiency virus type 1 (HIV-1), the retrovirus that is the main cause of AIDS, has been a puzzle ever since it was discovered by Barr -Sinoussi and her colleagues in 1983. A chimpanzee named Marilyn that died years ago has helped scientists solve the lingering mystery of the origin of AIDS. Researchers at the University of Alabama at Birmingham said that they have conclusive evidence that the HIV virus has spread on at least three separate occasions from chimpanzees to humans in Africa. One of the inter species transmissions launched the pandemic that now infects about 35 million people worldwide.

The chimp version of the AIDS virus, thought to be the grandfather of HIV, is called SIVcpz. It is extremely rare among chimps in U.S. lab colonies, apparently because they are removed from the wild at a young age and never exposed to the virus sexually. Recently scientists from the University reported that they have discovered the origin of HIV-1, the virus responsible for the global AIDS pandemic. A subspecies of chimpanzees native to west equatorial Africa has been identified as the original source of the virus. Although scientists have long suspected chimps as the source of AIDS, the absence of clear evidence prevented them from making the conclusion. Dr. Beatrice Hahn, the leading researcher, report was published in a February, 1999 issue of the journal Nature.

At a Conference on Retroviruses and Opportunistic Infections, Dr. David Ho and others from the Aaron Diamond AIDS Research Center at Rockefeller University presented evidence that the virus probably first infected people around 50 years ago. HIV-1's origin had been unclear. Although most scientists suspected that the virus descended from a primate species, only three chimpanzees infected with viruses related to HIV-1 had been documented, and one of these viruses correlated only weakly with HIV-1. When Dr Hahn and her collaborators recently identified Marilyn with SIVcpz, they decided to use this opportunity to carefully examine all four viruses and the animals from which they were derived. With sophisticated genetic techniques, they analyzed the four SIVcpz isolates and compared them with various HIV-1 viruses taken from humans.

They also determined the subspecies identity of the chimpanzees: three belonged to a subspecies Pan troglodytes troglodytes. The chimp subspecies lives in Cameroon, Equatorial Guinea, Congo and Central African Republic, the region where AIDS is thought to have started. The fourth, the chimpanzee infected with a virus most unlike HIV-1, belonged to an east African subspecies known as Pan troglodytes schweinfurt hii. As it turns out, the three isolates from the Pan troglodytes troglodytes chimpanzees strongly resemble the different subgroups of HIV-1. There are three major groups of HIV: the main (M) group comprises the majority of subtypes that have spread across the world; an outlier (O) group is found in Cameroon, Gabon and Equatorial Guinea; and a new group (N) was last year identified in two people in Cameroon. Their investigation also revealed that some of the viruses resulted from genetic recombination in the chimpanzees before they infected humans.

Their other significant find is that the natural habitat of these chimpanzees directly coincides with the pattern of the HIV-1 epidemic in this area of Africa. Putting all these pieces of the puzzle together, Dr. Hahn and her colleagues conclude that Pan troglodytes troglodytes is the natural reservoir of HIV-1 and has been the source of at least three independent occurrences of cross-species virus transmission events from chimpanzees to humans. The researchers believe that HIV-1 was introduced into the human population when hunters became exposed to infected blood. They also speculate that humans might still be at risk for cross-species transmission because of "bush meat"-the hunting and killing of chimpanzees and other endangered animals for human consumption-is still common practice in west equatorial Africa. If extreme measures are not taken soon, the species may become extinct before adequate scientific research is complete. This loss of species could rob the victims of the HIV virus from their only hope for successful treatment.

Preserving the wild chimpanzee populations will be crucial for further carefully designed studies to better understand how cross-species virus transmission occurs and how infected chimpanzees resist disease, studies that in turn may lead to new strategies for designing HIV drugs and vaccines. Chimps, which probably have carried the virus for hundreds of thousands of years, apparently do not get sick from it. Understanding why could help in the search for a cure, AIDS experts say. This species of chimpanzee is able to live naturally with the virus without contracting illness This is an important finding with significant potential", said Dr. Anthony Farci of the U.S. National Institute of Allergies and Infectious Diseases (NIAID), which helped fund the study.

"This virus infects a primate species that is 98 percent related to humans. This may allow us - if done carefully and in collaboration with primatologists to protect this endangered species - to study infected chimpanzees in the wild to find out why these animals don't get sick, information that may help us better protect humans from developing AIDS", he said. This new discovery could also lead to new tests that would discover new viruses in the biosphere before they are allowed to infect humans. One can only imagine the lives and suffering that would have been prevented if the HIV were discovered before it was allowed to infect humans.