New AIDS Vaccine To Undergo Human Trials For First Time

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Dr Robert Gallo is a name you’ve probably never heard of, but he’s the biomedical researcher who led the team responsible for unmasking the cause of AIDS (acquired immune deficiency syndrome). In 1984, he was catapulted to world fame for discovering that the human immunodeficiency virus (HIV) was the malevolent infectious force behind one of the most debilitating epidemics in human history. HIV is, to date, essentially incurable. However, over 30 years on from the monumental discovery, Dr Gallo still hasn’t stopped his scientific crusade to combat this virus. In his role as the director of the Institute of Human Virology (IHV), he is now launching the institute's first clinical trial of a vaccine for AIDS – a project that has been 15 years in the making.

The search for a vaccine against HIV and AIDS has been ongoing for decades. Vaccines – which characteristically contain a severely weakened form of the infectious microbe or its surface proteins – have been the most effective weapon in humanity’s fight against a variety of bacterial and viral diseases. Smallpox has been completely wiped from the face of the Earth by an extensive vaccination programme, saving millions of lives. Polio isn’t far behind, and – despite recent flare ups in areas that are poorly vaccinated due to unfounded scaremongering – measles is another viable candidate for eradication. HIV, however, has been impossible to vaccinate against.

Now, the IHV in Baltimore, Maryland, is hoping its experimental vaccine against AIDS proves promising. The human immune system seems to be unable to combat an HIV infection; consequently, except for one exceptional case, no one has ever recovered from the infection. With HIV's inherent ability to rapidly mutate and escape the immune system, conceiving an effective vaccine against it has been an enormous, seemingly insurmountable challenge.

When HIV infects a person, its surface protein binds to segments of another protein called the CD4 receptor, which is found on white blood cells. Using this holding point on the white blood cell as a staging post, it then begins to bind with a second receptor called a co-receptor. Once it has a grip on both it is able to infect the white blood cell and replicate itself.

Like other vaccines, this experimental AIDS inoculation – named the “full-length single chain” vaccine – contains a version of the surface protein of HIV, specifically bioengineered so that it links to a few segments of the CD4 receptors. As with every vaccine, the aim with this one is to generate antibodies – the proteins produced by the immune system that hunt down and neutralize viral or bacterial pathogens. These will bind with HIV’s surface protein while it is in the transitional state of establishing a foothold on the white blood cell, ultimately aborting the process and terminating the infection before the virus can infect the cell and replicate.

This vaccine is being led by IHV’s George Lewis, a professor of microbiology and immunology, and the director of the Division of Vaccine Research. This human trial, in what is known as a phase I study, has taken a long time to research and develop, as all vaccine trials do. The IHV wished to be cautious, wanting to be absolutely sure of its potential efficacy, before proceeding to human trials. Its pioneering director Dr Gallo insisted that they wanted “more and more answers before going into people,” as reported in Science.

AIDS-related causes killed 1.2 million people in 2014, according to the World Health Organization, and dying of AIDS is a slow, horrific process. This vaccine, if effective, could change the world.

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