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Wednesday, 20 November 2013 09:19

Super antibodies almost won HIV

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In AIDS patients as there is only one hope - to antiretroviral therapy, which is based on drugs that prevent HIV from reproducing. Genome recorded in the virus RNA and thus enter the cell it with reverse transcriptase enzyme (reverse transcriptase) makes a copy of its own DNA template RNA. Then, this DNA was self proteins cells begin RNA viral clone. If, for example, to suppress the work of the reverse transcriptase of the virus, it can not reproduce.

But even cocktails of antiretroviral drugs only help to translate the acute phase of the disease chronic. Such therapy can not do anything with the virus, which floats in the blood or in the cell is dormant. Therefore, researchers are looking for a way to get rid of the virus, rather than just suppressing its ability to reproduce. (By the way, the usual anti-HIV therapy is theoretically allows to get rid of the virus, but only under special conditions, and such cases are, unfortunately, rare.)

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HIV and human lymphocyte

When it comes to completely banish HIV, all agree that the best anti tool to be found here. On the one hand, it's simple: just find the immunoglobulins, which would learn viral envelope protein have been associated with him and would have signaled an immune killer cells that this complex must be destroyed. The problem, however, is that HIV has enormous variability, and antibodies usually catch only a certain proportion of the virus particles, for the same protein they endowed with a number of differences that make antibodies do not see it.

However, our immune system is still able to cope with such a variety of the virus , creating a broad-spectrum antibodies . The fact that the immune system can produce immunoglobulins that recognize more than 90 % of the species of HIV , scientists discovered in 2010, and this discovery , of course, has given all hope that AIDS is about to fall . But over time it became clear that such antibodies are rare and a huge amount of time , then only in response to a real infection - that is to provoke a synthesis of a vaccine of killed pathogen will not work.

Nevertheless, scholars have continued to work with the likes of antibodies. And not so long ago have found universal antibodies that appear much earlier and look simpler than those observed before - however, proved their versatility and low. But be sure to make yourself immune to produce such antibodies? The experiments showed the two research groups - Deaconess Medical Center Beth Israel and the National Institute of Allergy and Infectious Diseases (both - USA) - immunoglobulins broad-spectrum, just introduced into the blood, effectively reduce the level of HIV.

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HIV between epithelial cells (bottom) and lymphocyte (top)

Immediately it should be said that the group of Dan Baruch (Dan Barouch) and Malcolm Martin (Malcolm Martin) experimented with monkeys: macaques infected with simian-human hybrid HIV, which multiply in monkeys, but looked like a human virus. He served as a weapon against a broad-spectrum antibodies obtained from patients with AIDS.

Dan Baruch and his colleagues used a cocktail of three types of antibodies, and, as the researchers write in Nature, in the week of the virus level down so that it can not be detected! A similar result was also when used instead of a mixture of immunoglobulins only one of their kind. Once the content of such antibodies in the blood began to decline, the concentration of the virus rose again, but some monkeys it was still indistinguishably low even without the introduction of additional portions of antibodies.

In another study carried out by Malcolm Martin and his colleagues, we are talking about the same thing , but here researchers have used different types of antibodies against HIV. Again, the concentration of the virus in macaques fell for seven days prior to the indiscernible ( again: undetectable !) Level and remained so for 56 days, until the antibodies do not begin to fade. Then it all depended on how much virus was originally in monkeys , if small, following the disappearance of virus antibodies remained under the control of its own immunity of animals , and if it was originally much, the level began to rise.

Thus, as emphasized by the researchers, the virus disappeared from both the blood and other tissues, and no resistance to the administered antibodies, it appeared. (However, there was one exception: when the second study administered only one antibody and experimental monkey was a 3-year experience of cohabitation with the virus, it has a sustained viral strain.)

In both cases, scientists are not too long treated the virus with human antibodies because they were afraid that the immune system begins to resent monkeys against foreign immune proteins , and perhaps that was the reason that in most cases, the virus recovered . That is, it is not clear whether it is possible to make the effect of the " long-playing ". All this is clear only after a clinical trial , and as for the results described above , the enthusiasm of researchers can understand the first time in a living organism could so much lower level of viremia (alas , previous experiments with antibodies that were placed on humans and mice had a very unimpressive results ) .

What's next? The cost of antibodies is much higher than the anti-retroviral drugs, and to treat them more difficult. But the authors of the work suggest that such antibodies should be connected to conventional anti-HIV drugs: it will reduce the cost of treatment, and is likely to increase its efficiency - if antibodies to add substances harmful to reproduction of the virus in the cell.

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