HIV refers to RNA viruses
HIV refers to RNA viruses (it is based on RNA, not DNA). It is transmitted through sexual contact or blood and is introduced into white blood cells, white blood cells. HIV enters the cell through its surface, and then transfers its genetic information to it, thus forcing it to produce copies of the virus. After a few years, the immune system weakens, and a person becomes a victim of infectious diseases or cancer. HIV has recently spread beyond Africa – no more than 60 years ago. But his homeland is the Black Continent.
In Botswana, one in six is the carrier of HIV. The most interesting is how, according to forecasts, there will be an age distribution in this country by 2020. Those who in the seventies were 16 years old, now should be 50-60 years old. A typical age distribution in African countries is the predominance of the young population over the old one. And if you look at the forecast, then after a while the old people will hardly remain – until the venerable age they simply will not survive because of HIV. This is a big problem that requires reflection.
The evolution of HIV allows us not only to look for effective methods to prevent the spread of this virus, but, more importantly, it provides invaluable information about the evolution of viruses in general, and also about human advancement.
In 1867, Charles Darwin drew a famous scheme of the family tree of living organisms related to each other and descended from a certain extinct ancestor, symbolizing the mitigation of the offspring. We did the same with HIV, collecting information about virus strains from around the world. It turned out that, say, in Russia there is one group of human immunodeficiency viruses, different from the group that is pervasive in North America, and from the group that is pervasive in Africa. Here is an illustrative example of the modification of the offspring.
Thanks to the tree, we can trace the association of all these viruses with one ancestral virus and understand what it was. Also, this scheme allows us to study the development of differences in their genetic structure over a certain period. Having compiled a mathematical model, we can reconstruct the same virus that went beyond Africa in the 20s of the last century, guided by the speed of its mutation.
The incontrovertible evidence of evolution is fossils. It is difficult to imagine the fossils of the virus, but one American biologist went to the Congo and found in a tissue sample of a man who died in 1959 from an unknown disease, a strain of HIV that fit perfectly into the above-mentioned tree.
Now you could ask another question: where did HIV come from? Almost all human diseases come from animals – chimpanzees or gorillas have viruses that are similar to HIV. There are HIV strains originating from the chimpanzee immunodeficiency virus, last year they discovered strains originating from the gorilla immunodeficiency virus, there are strains derived from the smoky mangobei virus. That is, the virus was transmitted to humans at different times from different animals.