The mechanism of primate immunity will help create an effective vaccine against HIV
A group of microbiologists and geneticists from the University of Pennsylvania determined the reason for the lower spread of immunodeficiency virus (SIV) among monkeys and determined why in most cases it could not lead to the death of the animal. The findings of experts who have drawn attention to the extremely unusual structure of receptors of immune cells, were published in the journal PNAS.
The fact of the “recent” origin of HIV associated with the infection that has engulfed the world is still associated in people with a lot of mysteries. The most famous of these is the theory of the first transmission of a virus to humans from a primate in one of the regions of West Africa, where it was first discovered.
Scientists are increasingly talking about the extremely low probability of such a scenario. The successful evolution of the virus and its adaptation to work "in new conditions" should have taken more time. In addition, as is known, the monkey's immunodeficiency virus (SIV) is in most cases not fatal.
The group of Professor Khan, after examining tissue samples of several hundred wild chimpanzees, found a fairly simple explanation for the rapid evolution of the “ancestor” of HIV and its modifications to infect human immune cells, and also found out why SIV does not progress.
The specialists were interested in exactly which strains of SIVs affected different populations of primates, and whether there were differences between them and how the immune cells of the animals interacted with them.
Careful analysis allowed scientists to see a very interesting fact: the CD4 receptor, which HIV and SIV are used to penetrate cells, in chimpanzees had several variations at once that were completely different from each other in structure and, moreover, evenly distributed throughout the population.
Some of them "corresponded" to those types of SIVs that were used in monkeys' habitats, but other strains could not find a connection with the cells, because their receptors actively opposed this (they are surrounded by special carbohydrate chains that prevented the virus from connecting to the receptor).
Scientists are confident that the described properties of T-cells of chimpanzees simultaneously inhibit the spread of the virus throughout the population and protect the monkey's immunity from complete exhaustion. It was the absence of this mechanism in the human body that made it extremely vulnerable to the virus and affected the extremely rapid adaptation of HIV to new conditions.
As the results of the study showed, the presence of even one small mutation in the CD4 gene was able to drastically reduce the number of potentially dangerous for the body strains of SIV. However, the scientists emphasized that even such a mechanism does not provide absolute protection against infection: it is enough for the virus and the receptor to match - and the disease cannot be avoided.
However, the use of technology "variable" assembly of receptors in primates, experts say, will make human cells far less vulnerable to HIV attacks. This gives hope for the development of a new, highly effective vaccine against the virus.