DO NOT INFORMATION OVERLOAD JUST ANSWER THE QUESTIONS 1. Is being HIV positive t
ID: 206933 • Letter: D
Question
DO NOT INFORMATION OVERLOAD JUST ANSWER THE QUESTIONS
1. Is being HIV positive the same as having AIDS? Explain.
2. In what year was AIDS first discovered? In what year is AIDS thought to have originated?
3. Note there was a large gap of time between when AIDS thought to have originated and when it was first discovered. What could account for this large gap?
4. what is the difference between HIV-1 and HIV-2?
5. how is it thought that HIV-1 originated?
6. what country has the highest incidence of AIDS? (note Africa is NOT a country)
Explanation / Answer
HIV is a virus. AIDS is a condition caused by HIV.
You can have HIV without developing AIDS, and many people live for many years with HIV without ever developing AIDS. But if you have AIDS, you have to have HIV.
In 1983, scientists discovered the virus that causes AIDS.
The earliest known case of infection with HIV-1 in a human was detected in a blood sample collected in 1959 from a man in Kinshasa, Democratic Republic of the Congo. (How he became infected is not known.) Genetic analysis of this blood sample suggested that HIV-1 may have stemmed from a single virus in the late 1940s or early 1950s.
It is widely believed that HIV originated in Kinshasa, in the Democratic Republic of Congo when HIV crossed species from chimpanzees to humans. HIV was unknown and transmission was not accompanied by noticeable signs or symptoms.
HIV-1 and HIV-2 are two different viruses. HIV-1 is the main family of HIV and accounts for 95% of all infections worldwide. HIV-2 is mainly seen in a few West African countries. The spread in the rest of the world is negligible. Although HIV-2 generally progresses more slowly than HIV-1, some HIV drugs (NNRTIs like nevirapine and efavirenz) do not work against HIV-2.
HIV-1 is the thing that afflicts tens of millions of people throughout the world. HIV-1 is the pandemic scourge.
HIV-2 is both less transmissible and less virulent than HIV-1. HIV-2 is confined mostly to West African countries such as Senegal and Guinea-Bissau (the latter of which, during colonial times, was Portuguese Guinea), and to other areas connected socially and economically within the former Portuguese empire, including Portugal itself and southwestern India. People infected with HIV-2 tend to carry lower levels of virus in their blood, to infect fewer of their sexual contacts, and to suffer less severe or longer-delayed forms of immunodeficiency. Many of them don’t seem to progress to AIDS at all. And mothers who carry HIV-2 are less likely to pass it to their infants.
On a structural level HIV-1 and HIV-2 have important genetic differences. A technical description of the difference is that the vpu gene found in HIV-1 is replaced by the vpx gene in HIV-2. In addition, the protease enzymes from the two viruses, which are aspartic acid proteases and have been found to be essential for maturation of the infectious particle, share about 50% sequence identity.
On functional level, there is a difference between the two viruses in terms of how easy it is for the virus to infect someone. HIV-1 enters the immune system by attaching onto the CD4+ receptor found on the surface of certain white blood cells. HIV-2 has a harder time gaining such a foothold.
HIV is a type of lentivirus, which means it attacks the immune system. In a similar way, the Simian Immunodeficiency Virus (SIV) attacks the immune systems of monkeys and apes.
Research found that HIV is related to SIV and there are many similarities between the two viruses. HIV-1 is closely related to a strain of SIV found in chimpanzees, and HIV-2 is closely related to a strain of SIV found in sooty mangabeys.2
Did HIV come from monkeys?
In 1999, researchers found a strain of SIV (called SIVcpz) in a chimpanzee that was almost identical to HIV in humans. The researchers who discovered this connection concluded that it proved chimpanzees were the source of HIV-1, and that the virus had at some point crossed species from chimps to humans.
The same scientists then conducted more research into how SIV could have developed in the chimps. They discovered that the chimps had hunted and eaten two smaller species of monkeys (red-capped mangabeys and greater spot-nosed monkeys). These smaller monkeys infected the chimps with two different strains of SIV.
The two different SIV strains then joined together to form a third virus (SIVcpz) that could be passed on to other chimps. This is the strain that can also infect humans.
How did HIV cross from chimps to humans?
The most commonly accepted theory is that of the 'hunter'. In this scenario, SIVcpz was transferred to humans as a result of chimps being killed and eaten, or their blood getting into cuts or wounds on people in the course of hunting.5 Normally, the hunter's body would have fought off SIV, but on a few occasions the virus adapted itself within its new human host and became HIV-1.
There are four main groups of HIV strains (M, N O and P), each with a slightly different genetic make-up. This supports the hunter theory because every time SIV passed from a chimpanzee to a human, it would have developed in a slightly different way within the human body, and produced a slightly different strain. This explains why there is more than one strain of HIV-1.
The most studied strain of HIV is HIV-1 Group M, which is the strain that has spread throughout the world and is responsible for the vast majority of HIV infections today.
At an estimated 26.0 per cent, Swaziland has the highest HIV prevalence rate in the world,
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