Last updated May 29, 2018 at 9:57 am
A single injection has successfully provided up to 20 weeks of protection against HIV infection in monkeys, in a landmark US study.
Although successful campaigning has seen AIDS numbers drop globally, HIV remains to have no vaccine or cure. A new study provides an alternative treatment; researchers have demonstrated that one single injection of HIV-targeting antibodies can protect monkeys from the simian version of HIV (SHIV) infection for up to 20 weeks.
Previous studies have shown that individuals who are HIV-positive are able to develop broadly neutralising antibodies, which are proteins with protective properties, that block infection from a broad range of viral strains. Different antibodies are able to target certain features of the HIV virus. These antibodies are already being used clinically to reduce virus levels in HIV-positive people. They have being preclinically tested in monkeys to find out if they can prevent HIV infection altogether.
Putting two together
The experiment involved two specially modified antibodies that can neutralise HIV. The combination of the two antibodies was able to protect macaque monkeys for a median of 20 weeks. This was tested with repeated low dose virus challenges, and confirmed by regularly testing of the monkeys to detect the existing presence of the antibodies in their immune system. Individually, each antibody was also able to provide protection against SHIV.
In the combination treatment, nearly threefold less of each antibody than a single antibody injection was required. This is particularly important as antibodies can be expensive to produce. The combination of different antibodies is also realistically more beneficial due to the wide diversity of HIV strains.
One issue with using human antibodies in monkey studies like this is that the immune system of monkeys is already to produce anti-antibodies. This natural response clears out the injected human antibodies out of the system, and it may influence the results of how long the antibody can last in the body, and thus its ability to target the virus. In clinical studies, healthy human adults have failed to produce anti-antibodies.
Preventing HIV
In lieu of an effective vaccine (which involves a substance with the causative agent – in this case, HIV – or a synthetic replica), or the development of a vaccine in the near future, the researchers write that their research “could translate into an effective semiannual or annual immunoprophylaxis regimen for preventing HIV-1 infections in humans.”
The next step for this study is a planned extension towards a phase I clinical trial in humans.
This research is published in Nature Medicine.
