What type of HIV?
HIV is a lentivirus, and like all viruses of this type, it attacks the immune system. Lentiviruses are in turn part of a large group of viruses such as retroviruses. The name of lentivirus "literally means" slow virus "because it takes so long to produce negative effects in the body. They have been found in many different animals, including cats, sheep, horses and cattle. But the most interesting lentivirus in the investigation into the origin of HIV is the virus of the simian immunodeficiency virus (SIV) that affects monkeys.
So do not come from the HIV-SIV?
It is now widely accepted that HIV is a descendant of simian immunodeficiency virus, as some strains of SIV have a very close resemblance to HIV-1 and HIV-2, two types of HIV.
HIV-2 for example corresponds to SIVsm, a strain of simian immunodeficiency virus sooty mangabey in (also known as monkey white collar), who is from West Africa.
more virulent strain, the pandemic of HIV, namely HIV-1, was until recently difficult to place. Until 1999, when there is a match, which had been identified was SIVcpz, SIV in chimpanzees. However, this virus still had certain significant differences from HIV.
What happened in 1999?
In February 1999, a group of scientists from the University of Alabama1 announced they had found SIVcpz that was almost identical to HIV-1. This strain was found in frozen samples taken captive chimpanzees members of the subgroup known as Pan troglodytes troglodytes (P. t. troglodytes), which were once common in the African community.
Scientists (led by Paul Sharp of Nottingham University and Beatrice Hahn of the University of Alabama) made the discovery during a study of 10 years along the original virus. They argued that the tests have shown that chimpanzees were the source of HIV-1, and that the virus had crossed at one point species of chimpanzees to humans.
The final conclusions were published two years later in Nature magazine2. In this article, it was found that wild chimps became infected simultaneously with two simian immunodeficiency virus different than sex "viral" to create a third virus that can be transferred to other apes, and much more is able to infect humans, causing AIDS.
These two different viruses were back SIV that infected red mangabeys limited and we are in a better face up monkeys. They believe that the hybridisation took place inside chimps that have been infected with both strains of SIV after hunting and killing the two smaller species of monkeys.
They also found that the three "groups" of HIV-1 - namely Group M, N and O (see the tensions and subtypes page for more information) - is derived from the SIV in P. t troglodytes, and that each group represented on a separate "event" of chimpanzees to humans.
How HIV have crossed species?
Has long been known that certain viruses can pass between species. Indeed, the very fact that chimpanzees obtained SIV from two other species of primates shows how easy it is crossing can occur. Like the animals themselves, are equally sensitive. When the transfer of viruses between animals and humans takes place, is known as zoonosis.
Here are some of the most common theories about how it "zoonosis' took place, and how SIV became HIV in humans:
"Hunter" theory
the most commonly accepted theory is that the "hunter". In this scenario, SIVcpz was transferred to humans by chimpanzees are killed and eaten or their blood for the cuts or wounds on the hunter. Normally, the body of the fighter's combat SIV, but in some cases, it is adapted to a new human host and become HIV-1. The fact that there were a few different strains of HIV, each with slightly different genetic (most HIV-1 group M), will support this theory: every time he passed from chimpanzees to humans is developed in a little different how his body and therefore has a slightly different strain.
Article published in The Lancet in 20043, and also shows how retroviral transfer of primates hunters is still ongoing today. In a sample of 1099 people in Cameroon have discovered ten (1%) were infected with SFV (simian foamy virus), a disease which, like SIV, was thought to infect primates. All these infections were believed to have been acquired by the consumption of meat cut and monkeys. Discoveries like this led to calls for an outright ban on bushmeat hunting to prevent simian viruses to humans.
The oral polio vaccine (OPV) theory
Other more controversial theories have argued that HIV was transferred iatrogenic (ie via medical interventions). Particularly good is that the idea of vaccination against the spread of polio has played an important role in the transfer.
In his book, The River, the journalist Edward Hooper suggests that HIV can be attributed to oral polio vaccine called Chat, given to about one million people in the Belgian Congo, Rwanda and Burundi in 1950. Repetition, a live vaccine against polio must be grown in living tissue, and Hooper is the belief that the cat has been grown in kidney cells taken from local chimps infected SIVcmz. This, he said, would lead to contamination of the vaccine with chimp SIV, and then a large number of people infected with HIV-1.
Many people have questioned the theory of Hooper, and argue that the local strain infected chimpanzees do SIVcmz which is closely associated with HIV. In addition, the vaccine appears to be insufficient to cause infection in most people (SIV / HIV needs to get directly into the bloodstream causing infection - mouth and throat generally act as barriers to good viruses) .4
In February 2000, the Wistar Institute in Philadelphia (one of the largest producers of vaccines IM) announced that it has discovered in its stores a vial of vaccine against polio, which were used in the program. The vaccine was then tested in April 2001 announced that there was no evidence of HIV or chimpanzee SIV.5 second analysis confirmed that only macaque monkey kidney cells, which can be infected with SIV and HIV were used for Chat.6 Although a single vial of a large number, it means that the OPV theory remains unproven.
The fact that the OPV theory accounts for only one group (M) with different groups of HIV also suggests that the transfer must also be in a different way, like the fact that HIV seems to exist in humans before the vaccine trials were never realized OUT. Learn more about HIV when it arises can be found below.
contaminated needle theory
It is an extension of the original "hunter" theory. In 1950, the use of disposable plastic syringes became commonplace around the world as a cheap, sterile way to administer medications. However, Africa is working on health care, vaccinations and other medical programs, large quantities of syringes needed would be very expensive. It is therefore likely that the syringe was used to introduce many patients without sterilization between the two. It quickly transmit viral particles (in the blood of a hunter for example) from one person to another, creating huge potential for the virus to mutate and repeat for each new person entered, even if people of SIV infection is not yet converted to HIV.
Theory of Colonialism
Colonialism and "Heart of Darkness' theory, is one of the most recent theory, which was introduced into the debate. Then again, based on the premise of basic hunter, but more thoroughly explains how this original infection could lead to epidemics. For the first time proposed in 2000 by Jim Moore, an American specialist in primate behavior, which published its findings in the journal AIDS Research and Human Retroviruses.7
In the late 19th and early 20th century, a large part of Africa ruled by colonial powers. In areas such as French Equatorial Africa and Belgian Congo, colonial rule was particularly difficult, and many Africans were forced to labor camps, where sanitation was poor, with inadequate nutrition and physical demands are enormous. These factors alone would be sufficient for a person in poor health, so SIV could easily have infiltrated the labor market and take advantage of their weakened immune systems from HIV. Homeless and sick chimpanzee with SIV may decide to accommodate additional source of food for the workers.
Moore also believes that many workers would be inoculated with unsterile needles against diseases such as smallpox (to keep them alive and working), and most camps for prostitutes working staff maintain a happy, creating many opportunities for transmission. Many workers would not have died before they developed the first symptoms of AIDS, and those who do not get sick does not look like any other disease in the population have changed. Even if they were established, all evidence (including the medical records) that the camps existed was destroyed to hide the fact that the gradual 50% of the population have not been cleared.
The last element of Moore uses to support his theory is that labor camps were set up on time, that HIV was first believed to have gone to the population - in early 20th century.
Conspiracy Theory
Some argue that HIV is a conspiracy theory "or he is a man." A recent study in the United States, for example, identify a significant number of African-Americans who believe that HIV has been achieved in the biological warfare program, aimed at destroying a large number of blacks and gays people.8 Many would argue, is under the auspices of the federal government "Special Virus Cancer Program (SCVP), possibly with the help of CIA. combined in this theory is the belief that the spread of the virus (intentionally or not) to thousands of people worldwide through the vaccination program against smallpox, and hepatitis B vaccine trials gay . Although none of these theories can be definitively disproved, the evidence to back them up is usually based on hypothesis and speculation, and ignores the clear link between SIV and HIV, or that the virus been identified in humans in 1959.
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