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The Origin of HIV

andrelle's picture

      As of 2006, there are 32.2 million adults and 2.3 million children living with AIDS.  For a disease that has only been discovered recently, it has caused an alarming number of deaths.  HIV/AIDS affect people all over the world and it will continue to kill people at an alarming rate until a cure or vaccine is found.  Although, those who are affected with AIDS are living longer due to antiviral drugs, not everyone have access to those drugs and the amount of people that are being affected continue to climb every year.  The first case of HIV was recognized in the early 1980s in the United States, and since then the origin of HIV has not been clear, there are simply several theories with little compelling evidence.     

Every one now agrees that HIV causes AIDS and since that connection has been made, there has been a quest for the origin of HIV in humans.  HIV is a form of lentivirus, which attacks the immune system.  Lentivirus are commonly found in animals with “the most interesting lentivirus in terms of the origin of the investigation is the Simian Immunodeficiency Virus (SIV) that affects monkeys.”(1)  Presently, it is widely accepted that HIV is a descendant of SIV because certain strains of SIVs resemble HIV-1 and HIV-2.  The fact that the strains simply resemble each other creates uncertainty in the mind, and automatically reminds one that scientist are simply referring and does not know for sure.  Since this type of virus occurs in animals, the question then becomes how the virus cross-over to humans.     

 There have been incidents in which viruses are passed between species and so “as animals ourselves, we are just acceptable.”(1)  Thus, scientists felt the need to find out how exactly this exchange occurs, and so there exist a number of theories as to how exactly this happened.  The most accepted theory suggest that humans contract SIV from hunting chimpanzees, and that by eating chimpanzees and killing chimps the disease got into their system.  Normally, humans would fight off the virus, but on a few occasions it was able to adapt in the new host’s body.  This theory seems fairly simple, and could be possible if it could be proven that SIV is directly related to HIV.  The relationship between SIV and HIV keeps changing all the time which then creates doubt as to how close to the truth the evidence is.  In 1999, a group of scientists found a new strain of SIV named SIVgsn and it is thought to be the closest strain to HIV-1 that seems to originate in monkeys and those monkeys then infects Chimpanzee which then infects humans.(3)     

It would not be surprising if in a few years, scientist find another strain that is yet closer to the HIV-1 strain than the ones that we have found before.  It does make sense that there are several strains of virus and that one gives rise to the other.  Viruses have been known to reproduce and to learn how to strive in new environments.  This occurred with tuberculosis, where new strains of the virus would reproduce and produce stronger strains that were immune to the drugs.  Scientists claim that they “finally tracked its [HIV] original source to two colonies of chimpanzees in a corner of Cameroon.”(2)  The lingering question that remains is exactly how close is the SIV virus to the HIV virus? Even scientists disagree among themselves about the relationship between viruses, and so how sure can we really be about the relationship between SIV and the HIV virus.    

  Scientist has claimed to find further evidence that links HIV to monkeys.  Humans seem to only be missing a single change in their gene to effectively block HIV infection, and apparently rhesus monkeys possess the gene that allows it to effectively block the virus.(4)  The report however does not go into details as to how exactly scientists were able to discover this gene.  There has not been a case of HIV found in monkeys yet, and so how do we know that the rhesus monkeys are able to block the infection.  Furthermore, the very fact that humans and monkeys carry a different genetic makeup implies that the virus might not manifest itself in the same way in both species. It seems absurd to compare two species that are very different from one another.  The very fact that HIV is thought to be related to SIV who when transferred to humans causes AIDS proves that species react differently to different viruses.     

 There are many who does not believe in the theory that SIV got transferred to humans accidentally.  The most popular alternative view is that the polio vaccine which had to be cultivated in living tissue that came from kidney cells from chimps was contaminated with SIV. (1)  The Wistar institute refutes that argument by testing a phial of polio vaccine that was used at the time and the test shows that there were no signs of HIV and SIV.  This test does not disprove the claim because it was only done on one phial and so who’s to say that the other phials were not contaminated.  There are also a number of theories that are simply other version of the story that SIV was transferred to humans from hunting Chimpanzees.     

 The search for the origin of HIV is a perfect example of how scientists are simply coming up with stories based on observations.  Scientists were able to observe a resemblance between the virus HIV, and that which is found in Chimps call SIV, and from that simple observation emerges several stories to fit that observation.  The fact that HIV is a virus that can change and morph into other things makes it very difficult to pinpoint exactly when it emerged.  Thus, scientists can continue to do research in hopes pf proving themselves wrong in order to bring us closer to the true origin of HIV.  And the hope is that once we find how HIV evolved, and then maybe we can figure out how to stop it.