The Orgins of AIDS & HIV and the first cases of AIDS
Debate around the origin of AIDS has sparked considerable interest and controversy since the beginning of the epidemic. However, in trying to identify where AIDS originated, there is a danger that people may try and use the debate to attribute blame for the disease to particular groups of individuals or certain lifestyles.
The first cases of AIDS occurred in the USA in 1981, but they provide little information about the source of the disease. There is now clear evidence that the disease AIDS is caused by the virus HIV. So to find the source of AIDS we need to look for the origin of HIV.
The issue of the origin of HIV could go beyond one of purely academic interest, as an understanding of where the virus originated and how it evolved could be crucial in developing a vaccine against HIV and more effective treatments in the future. Also, a knowledge of how the AIDS epidemic emerged could be important in both mapping the future course of the epidemic and developing effective education and prevention programme.
What type of virus is HIV?
HIV is part of a family or group of viruses called lentiviruses. Lentiviruses other than HIV have been found in a wide range of nonhuman primates. These other lentiviruses are known collectively as simian (monkey) viruses (SIV) where a subscript is used to denote their species of origin.
So where did HIV come from? Did HIV come from an SIV?
It is now generally accepted that HIV is a descendant of simian (monkey) immunodeficiency virus (SIV). Certain simian immunodeficiency viruses bear a very close resemblance to HIV-1 and HIV-2, the two types of HIV.
For example, HIV-2 corresponds to a simian immunodeficiency virus found in the sooty mangabey monkey (SIVsm), sometimes known as the green monkey, which is indigenous to western Africa.
The more virulent strain of HIV, namely HIV-1, was until very recently more difficult to place. Until 1999 the closest counterpart that had been identified was the simian (monkey) immunodeficiency virus that was known to infect chimpanzees (SIVcpz), but this virus had significant differences between it and HIV
So what happened in 1999?
Are chimpanzees now known to be the source of HIV?
In February 1999 it was announced1 that a group of researchers from the University of Alabama had studied frozen tissue from a chimpanzee and found that the simian virus it carried (SIVcpz) was almost identical to HIV-1. The chimpanzee came from a sub-group of chimpanzees known as Pan troglodytes troglodytes, which were once common in west-central Africa.
It is claimed by the researchers that this shows that these chimpanzees were the source of HIV-1, and that the virus at some point crossed species from chimpanzees to human. However, it was not necessarily clear that chimpanzees were the original reservoir for HIV-1 because chimpanzees are only rarely infected with SIVcpz.
The findings of this 10-year long research into the origin and evolution of HIV by Paul Sharp of Nottingham University and Beatrice Hahn of the University of Alabama were published in 20032. They concluded that wild chimps became infected simultaneously with two simian immunodeficiency viruses (SIVs) which had "viral sex" to form a third virus capable of infecting humans and causing AIDS.
Professor Sharp and his colleagues discovered that the chimp virus was an amalgam of the SIV infecting red-capped mangabeys and the virus found in greater spot-nosed monkeys. They believe that the hybridisation took place inside chimps that had become infected with both strains of SIV after hunting and killing the two smaller species of monkey.
How could HIV have crossed species?
It has been known for a long time that certain viruses can pass from animals to humans, and this process is referred to as zoonosis.
The researchers concluded that HIV could have crossed over from chimpanzees as a result of a human killing a chimp and eating it for food.
Some other rather controversial theories have contended that HIV was transferred iatrogenically i.e. via medical experiments. One particularly well publicised theory is that polio vaccines played a role in the transfer.
The journalist Edward Hooper has suggested that HIV could be traced to the testing of an oral polio vaccine called Chat as batches of the Chat vaccine may have been grown in chimp kidney cells in the Congo, the Wistar Institute and Belgium. That could have resulted in the contamination of the vaccine with chimp SIV, the simian version of HIV-1. This vaccine was then given to about a million people in the Belgian Congo, Ruanda and Urundi in the late 1950s.
However, in February 2000 the Wistar Institute in Philadelphia announced that it had discovered in its stores a phial of polio vaccine that had been used as part of this polio vaccination program. The vaccine was subsequently analysed and in April 2001 it was announced3 that no trace had been found of either HIV or chimpanzee. A second analysis4 confirmed that only macaque monkey kidney cells, which cannot be infected with SIV or HIV, were used to make Chat.
What is crucial in regard to the credibility of any theory is the question of when the transfer took place.
Is there any evidence of when the transfer took place?
During the last few years it has become possible not only to determine whether HIV is present in a blood or plasma sample, but also to determine the particular subtype of the virus. Studying the subtype of virus of some of the earliest known instances of HIV infection can help to provide clues about the time of origin and the subsequent evolution of HIV in humans.
Three of the earliest known instances of HIV infection are as follows:
A plasma sample taken in 1959 from an adult male living in what is now the Democratic Republic of Congo
HIV found in tissue samples from an American teenager who died in St. Louis in 1969.
HIV found in tissue samples from a Norwegian sailor who died around 1976.
Analysis in 1998 of the plasma sample from 1959 was interpreted5 as suggesting that HIV-1 was introduced into humans around the 1940s or the early 1950s, which was earlier than had previously been suggested. Other scientists have suggested that it could have been even longer, perhaps around 100 years or more ago.
In January 2000, the results of a new study presented at the 7th Conference on Retroviruses and Opportunistic Infections, suggested that the first case of HIV infection occurred around 1930 in West Africa. The study was carried out by Dr Bette Korber of the Los Alamos National Laboratory. The estimate of 1930 (which does have a 20 year margin of error), is based on a complicated computer model of HIV's evolution.
Debate around the origin of AIDS has sparked considerable interest and controversy since the beginning of the epidemic. However, in trying to identify where AIDS originated, there is a danger that people may try and use the debate to attribute blame for the disease to particular groups of individuals or certain lifestyles.
The first cases of AIDS occurred in the USA in 1981, but they provide little information about the source of the disease. There is now clear evidence that the disease AIDS is caused by the virus HIV. So to find the source of AIDS we need to look for the origin of HIV.
The issue of the origin of HIV could go beyond one of purely academic interest, as an understanding of where the virus originated and how it evolved could be crucial in developing a vaccine against HIV and more effective treatments in the future. Also, a knowledge of how the AIDS epidemic emerged could be important in both mapping the future course of the epidemic and developing effective education and prevention programme.
What type of virus is HIV?
HIV is part of a family or group of viruses called lentiviruses. Lentiviruses other than HIV have been found in a wide range of nonhuman primates. These other lentiviruses are known collectively as simian (monkey) viruses (SIV) where a subscript is used to denote their species of origin.
So where did HIV come from? Did HIV come from an SIV?
It is now generally accepted that HIV is a descendant of simian (monkey) immunodeficiency virus (SIV). Certain simian immunodeficiency viruses bear a very close resemblance to HIV-1 and HIV-2, the two types of HIV.
For example, HIV-2 corresponds to a simian immunodeficiency virus found in the sooty mangabey monkey (SIVsm), sometimes known as the green monkey, which is indigenous to western Africa.
The more virulent strain of HIV, namely HIV-1, was until very recently more difficult to place. Until 1999 the closest counterpart that had been identified was the simian (monkey) immunodeficiency virus that was known to infect chimpanzees (SIVcpz), but this virus had significant differences between it and HIV
So what happened in 1999?
Are chimpanzees now known to be the source of HIV?
In February 1999 it was announced1 that a group of researchers from the University of Alabama had studied frozen tissue from a chimpanzee and found that the simian virus it carried (SIVcpz) was almost identical to HIV-1. The chimpanzee came from a sub-group of chimpanzees known as Pan troglodytes troglodytes, which were once common in west-central Africa.
It is claimed by the researchers that this shows that these chimpanzees were the source of HIV-1, and that the virus at some point crossed species from chimpanzees to human. However, it was not necessarily clear that chimpanzees were the original reservoir for HIV-1 because chimpanzees are only rarely infected with SIVcpz.
The findings of this 10-year long research into the origin and evolution of HIV by Paul Sharp of Nottingham University and Beatrice Hahn of the University of Alabama were published in 20032. They concluded that wild chimps became infected simultaneously with two simian immunodeficiency viruses (SIVs) which had "viral sex" to form a third virus capable of infecting humans and causing AIDS.
Professor Sharp and his colleagues discovered that the chimp virus was an amalgam of the SIV infecting red-capped mangabeys and the virus found in greater spot-nosed monkeys. They believe that the hybridisation took place inside chimps that had become infected with both strains of SIV after hunting and killing the two smaller species of monkey.
How could HIV have crossed species?
It has been known for a long time that certain viruses can pass from animals to humans, and this process is referred to as zoonosis.
The researchers concluded that HIV could have crossed over from chimpanzees as a result of a human killing a chimp and eating it for food.
Some other rather controversial theories have contended that HIV was transferred iatrogenically i.e. via medical experiments. One particularly well publicised theory is that polio vaccines played a role in the transfer.
The journalist Edward Hooper has suggested that HIV could be traced to the testing of an oral polio vaccine called Chat as batches of the Chat vaccine may have been grown in chimp kidney cells in the Congo, the Wistar Institute and Belgium. That could have resulted in the contamination of the vaccine with chimp SIV, the simian version of HIV-1. This vaccine was then given to about a million people in the Belgian Congo, Ruanda and Urundi in the late 1950s.
However, in February 2000 the Wistar Institute in Philadelphia announced that it had discovered in its stores a phial of polio vaccine that had been used as part of this polio vaccination program. The vaccine was subsequently analysed and in April 2001 it was announced3 that no trace had been found of either HIV or chimpanzee. A second analysis4 confirmed that only macaque monkey kidney cells, which cannot be infected with SIV or HIV, were used to make Chat.
What is crucial in regard to the credibility of any theory is the question of when the transfer took place.
Is there any evidence of when the transfer took place?
During the last few years it has become possible not only to determine whether HIV is present in a blood or plasma sample, but also to determine the particular subtype of the virus. Studying the subtype of virus of some of the earliest known instances of HIV infection can help to provide clues about the time of origin and the subsequent evolution of HIV in humans.
Three of the earliest known instances of HIV infection are as follows:
A plasma sample taken in 1959 from an adult male living in what is now the Democratic Republic of Congo
HIV found in tissue samples from an American teenager who died in St. Louis in 1969.
HIV found in tissue samples from a Norwegian sailor who died around 1976.
Analysis in 1998 of the plasma sample from 1959 was interpreted5 as suggesting that HIV-1 was introduced into humans around the 1940s or the early 1950s, which was earlier than had previously been suggested. Other scientists have suggested that it could have been even longer, perhaps around 100 years or more ago.
In January 2000, the results of a new study presented at the 7th Conference on Retroviruses and Opportunistic Infections, suggested that the first case of HIV infection occurred around 1930 in West Africa. The study was carried out by Dr Bette Korber of the Los Alamos National Laboratory. The estimate of 1930 (which does have a 20 year margin of error), is based on a complicated computer model of HIV's evolution.
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Miss P. You must get so tired listening to your own excuses. Why don't you try telling things straight up for a change instead of always changing around what you say, and continuously contradicting yourself. You might actually find you have a few supporters.