This is because HIV, which is the beginning of the AIDS virus, breaks down the immune system enough that the immune system allows the AIDS virus to move in. This .
History of AIDS 6.
theory is believed because the HIV virus is part of a group of viruses called lentivirus, which is found in species other than humans. This virus, simian immune deficiency (SIV), is found most commonly in simian, or monkeys. .
In February of last year, a group of researchers studied a frozen tissue sample from a chimpanzee. They found that the virus the chimpanzee had (SIVcpz) was practically identical to the HIV-1 virus. These chimpanzees are common in west central Africa. Because SIVcpz and HIV-1 are so similar, researchers believe that at some point the HIV-1 virus crossed from chimpanzees to humans in a process called zoonosis, which is the passing of a virus from animals to humans. Because these chimpanzees rarely are infected with SIVcpz, researchers are still unsure that they are the carriers of the HIV-1 virus. They now think that there may be a third species infecting both humans and chimpanzees, but researchers aren't sure what that species is. For now, they think the virus crossed when man killed infected chimpanzees and ate the meat, allowing the virus to transfer from monkeys to humans. It is generally accepted that HIV is a descendant of the simian immunodeficiency syndrome virus because of the close resemblance of HIV-1 and SIV (Kanabus & Allen, 2000). .
The other form of HIV, HIV-2 "corresponds to a simian immunodeficiency virus found in the sooty mangabey monkey, sometimes known as the green monkey, .
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which is indigenous to western Africa", says Kanabus and Allen (2000). Another theory that researchers are considering is that HIV was transferred through medical experiments. They believe that polio vaccines were made up of infected monkey kidneys, but accidentally infecting humans with the HIV virus (Kanabus & Allen, 2000).