Experimental HIV RNA vaccine successfully tested in animals

(ORDO NEWS) — Scientists at the US National Institute of Allergy and Infectious Diseases (NIAID) have successfully tested a new HIV RNA vaccine in animals. The treated macaques had an almost 80 percent lower risk of infection than the unvaccinated. Paolo Lusso and his colleagues write about this in an article published in the latest issue of the journal Nature Medicine .

The experimental vaccine was created with the participation of specialists from the Moderna company and, in principle, works in the same way as its RNA vaccine against the new coronavirus. The particles of the vaccine deliver messenger RNA molecules that encode the virus protein into the cells of the body. The cells at the injection site “mechanically” begin to produce it, causing the immune system to react. In the case of the HIV vaccine, two important proteins for this virus are used – Env and Gag.

Experiments on mice have shown that a couple of injections of the drug are enough for them to develop neutralizing antibodies. The authors noted that, unlike many previous similar developments, their vaccine leads to the synthesis of an Env protein in the body, which practically does not differ from the form in which it exists in the envelope of a real virus. This makes the immune defense more reliable. Next, scientists conducted experiments on macaques.

Several groups of animals received the first injection, and then, throughout the year, a series of “booster” ones, which contained mRNA of the Env and Gag proteins of different strains of HIV. As conceived by the researchers, this was to stimulate the immune system to produce more “universal” antibodies. By attacking the most conservative, stable regions of the virus, they are able to protect against a wide range of its varieties.

No serious side effects were noticed after the injection. By the 58th week, all vaccinated animals developed antibodies that “in vitro” successfully neutralized representatives of 12 HIV strains. In addition, macaques showed a powerful response from T cells, indicating that they learned to recognize the virus for attack.

Beginning at week 60, the animals were exposed to the infection by weekly administration of a modified Simian-Human Immunodeficiency Virus (SHIV). Primates do not infect HIV themselves, and for such studies a kind of “hybrid” was obtained – between the human virus and its close relative (SIV), which infects wild primates.

After 13 weeks, two of the seven test monkeys remained uninfected. In the rest, the infection began, but still noticeably later than usually occurs with unvaccinated animals – on average, at the eighth week, and not at the third. This shows that the immunity of such macaques coped with the attacks of the virus for a long time and did not lose immediately.

According to scientists, they plan to further refine their vaccine and again test its effectiveness and safety. If the experiments are again so successful, you can move on to clinical trials on volunteers. Meanwhile, clinical trials of another HIV vaccine, HIVconsvX , are underway in several African countries since the summer of 2020 .


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