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Is it possible to make a vaccine against HIV?

Using the speed of vaccination, the immune system want to teach to develop a rare type of antibodies that effectively neutralize HIV.


Electron micrograph of T-cells of the immune system infected with HIV. Yellow cones – the place where the viral particles leave the cell. (Photo: Flickr.com / NIAID.)

HIV prevalence among the adult population of the world according for 2015. (Illustration: the who.)

Electron micrograph of T-cells of the immune system infected with HIV. Yellow cones – the place where the viral particles leave the cell. (Photo: Flickr.com / NIAID.)

HIV prevalence among the adult population of the world according for 2015. (Illustration: the who.)”

According to the world health organization, in 2016 with HIV worldwide lived to 36.7 million people, 1.8 million were infected, and 1 million died of fully developed AIDS.

Medicine, which is completely destroyed HIV does not exist yet . Antiretroviral drugs that infected people have to take for life, inhibit the replication of the virus, but entirely to destroy the can’t. The fact that when the HIV enters the cell, it integrates into DNA, where it becomes inaccessible to medication and invisible to the immune system. There he can quietly “sit” and do not begin to reproduce until a safe moment.

Know of only one case of complete cure from HIV. Timothy brown, known as “the Berlin patient” in 2007 underwent bone marrow transplantation (recall that the bone marrow reservoir of immune cells) from a donor who had natural resistance to HIV. (The donor was from 1% of the lucky ones whose cells contain the receptor through which HIV gets them.) From the first day after transplantation, the patient stopped taking antiretroviral drugs and more to them did not come back, and in the future, the virus had never been able to find in any form.

Unfortunately, the case of Timothy brown is the exception. Other patients completely get rid of the virus from happening, besides the replacement of the infected immune system through transplantation from a donor is a very difficult and risky procedure.

HIV also can be combated by methods of gene therapy. The infected man is taken T cells from the blood, and edit their genome: using CRISPR/Cas9 (about which we repeatedly wrote) deletes the gene of the receptor, which is absent in people with natural resistance to HIV. As you can guess, in fact in this direction is much more complicated than it sounds, and yet of the molecular-genetic cure for HIV too early.

But as you know, to prevent disease rather than to treat it – in other words, for HIV it would be good to have the vaccine. However, as in the case of medication, 30 years of research, vaccines against it have not crowned success. When vaccination immunity should remember the typical molecular characteristics of the virus. But viruses easily mutate, and HIV mutates especially quickly due to the fact that the enzyme that it uses to copy its genetic information, makes a lot of mistakes.

Within a year after infection, the HIV population can reach the same genetic diversity that accrues during the same time the flu virus across the world. Therefore, a new flu vaccine we have every year, and vaccines against HIV are not present at all. For this reason, the body is unable to overcome HIV on their own. The immune system cannot keep up with the variability of the virus: while she manufactures antibodies against some genetic variants that already breed other, against which antibodies do not work.

But relatively recently, the hope for a vaccine appeared again, when researchers discovered a special type of antibody – neutralizing antibodies with broad spectrum of action. They are highly mutated (changed) in comparison with conventional antibodies and are directed against conservative sites of the virus (that is, the weakest change from generation to generation). In recent studies it was found that they are able to neutralize up to 98% of all genetic variants of HIV. Immune system at some point she began to produce these antibodies, but this time comes a few years after infection too late.

The staff of the Institute for Allergy and immunology in La JOLLA and the SCRIPPS Institute have developed a vaccine strategy that teaches the immune system to produce antibodies wide spectrum. To understand what do you mean, you need to submit, how do immune cells start to synthesize antibodies against the pathogen.

Antibodies produced by b-lymphocytes. Thus they can interact with foreign molecules, including viral proteins. We constantly appear In cells with different receptors for the recognition of strangers, so any virus must exist In the cells that grab the molecules. Viral material In the cells absorb and transform within ourselves and put out on its surface.

In order for the case went on, the cell needs to communicate with the T-cell. T-cell fits In the cell, recognizes its own molecules and molecules of viral material that it is exposed, and now the cell gets “good” for further struggle. (If the interaction between T – and b-cells was somehow not so In the cage before something was done wrong and T-cell it will not activate.)

Now, In cells that have received permission to fight the virus, trying to make sure to tie it as closely as possible and stronger. They begin to divide, and each division mutate, so, each new b-cell receptor changes slightly, and cells with new buds again are selected in the interaction with T-cells.

If slightly changing the receptor detects the virus even better, In-cell, in which he did it, continues to share further. And only after many rounds of this natural selection b cells with the best receptors begin to produce antibodies (which is in structure identical to the receptor).

Robert Abbott (Robert K. Abbott) and his colleagues propose to impact not just on the selection process. They proceed from the fact that almost all of people in the immune system, there is a certain number of b-cells broad-spectrum (previously, the researchers found that the proportion of cells approximately one cell per million). If the goal of vaccination is to make b cells of a broad spectrum were selected instead of conventional, which, although polished is for specific viral genetic variants, but quickly become obsolete.

Vaccination itself is a multistage procedure in which the body is injected virus-like constituents gradually changing composition. Each step should bring the immune system to producing coveted type of antibodies. In the words of one of the researchers, everything that happens looks as if cells are able to recognize squares, are taught to recognize circles, but taught them that using pentagons.

Human-designed strategy had, so far, the experiments are limited to mice, and preliminary results can be found in an article in Immunity. To talk about full-fledged vaccine against HIV is still very early, but at least there is hope that it really will be able to create.

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