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Why is the vaccine against AIDS so difficult to create?
Last reviewed: 16.10.2021
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For many decades, the search for a vaccine against HIV was similar to the search for the Holy Grail.
However, despite years of research and multimillion investment in research, the goal has not yet been achieved.
A recent study by scientists at the University of Oregon on Science and Health gave an explanation of why a slightly weakened, safe Simian Immunodeficiency Virus, similar to the human immunodeficiency virus (HIV), could prevent further infection of rhesus monkeys with a strong virulent strain, using such a technology remained risky, because the overly weakened virus did not produce any effect at all.
The study was conducted at the Institute of Vaccine and Gene Therapy and was published in the journal Nature Medicine.
Traditionally, there are two ways to create vaccines to fight infectious diseases. In the first case - live, but weakened strains that are not strong enough to provoke the disease, but the immune system reacts to them, is activated, and in the future can detect a similar full-fledged virus and effectively fight it. In the second case, dead forms of the strain are used. The principle of action of the vaccines of these two species is the same.
In the early 1990s, a slightly weakened form of the monkey immunodeficiency virus demonstrated the ability to prevent infection of individual primates with a dangerous full-fledged virus in the future, but in some individuals the vaccine itself caused AIDS. Attempts to further weaken the virus did not bring success - the vaccine simply lost its effectiveness.
Therefore, the task of scientists remains to find the golden mean: the creation of a vaccine that will not be too strong (otherwise it will lead to AIDS) or too weak (otherwise it will not be effective). Perhaps the study in question is a big step forward on this complex scientific path.
A group of scientists led by the director of the Institute for Vaccine and Gene Therapy, Louis Picker, found that antiviral T cells protect against infection, which are stored in large quantities in the lymphoid tissue as long as the weakened virus lives. If the virus is too weak or dies, then the T cells become less active, and the body loses its previous protection. Therefore, unlike most other vaccines, an HIV vaccine can probably only be effective with a constant presence in the body.
The Picker group has perfected another persistent virus called cytomegalovirus (CMV), which can be used to increase the effectiveness of fighting the body's immune system with viruses that cause AIDS. In May 2011, scientists conducted a study that confirmed the effectiveness of the experimental vaccine. She completely controlled the immunodeficiency virus in a significant number of infected monkeys.
"This is a huge step forward. We were impressed with the results, "said Wayne Coff, the head of the International AIDS Vaccine Initiative Foundation. "This drug allows you to fully control the process, under its influence, immunity can drive the virus out of the body."
Unlike the previously used experimental drug with adenovirus AAV, which did not prevent the development of HIV infection, the modified cytomegalovirus is a permanent virus, that is, it remains in the body forever, while it practically does not cause symptoms and provokes very strong cellular reactions. Louis Picker hopes that this vaccine can stop the development of HIV infection in humans.