Experimental HIV Vaccine Successfully Produces Neutralizing Antibodies to the Virus

Tested on rabbits, the vaccine produced antibodies to at least two HIV strains.

We may be one step closer to an HIV vaccine. A test carried out by Scripps Research, and the non-profit vaccine research organization IAVI has demonstrated that antibodies that neutralize a number of HIV virus strains can be successfully elicited. 

Published in Immunity on November 12, the study showed that this experimental vaccine targeted at least two critical sites of the virus. 

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What is HIV and how prominent is it?

The ever-changing, and rapidly mutating HIV virus was first identified in 1983. Since then, researchers have been working hard to find successful methods to eradicate the virus. 

UNAIDS has disclosed that 37.8 million people worldwide are currently living with HIV, that 1.7 million people were newly infected by it in 2018, and that approximately 35 million people have died from AIDS so far, which is caused by HIV infection.

The creation of antiviral drugs has meant that HIV-infected people can live with the virus, and that their ability to transmit it to others is reduced. Unfortunately, no drug has yet been created that clears the virus. 

The need for a preventative and an affordable vaccine has been a top priority for researchers looking to eliminate HIV as a major public health threat.

One such team of researchers is led by Richard Wyatt, a professor in the Department of Immunology and Microbiology at Scripps Research.

Wyatt and his team have conducted tests on an anti-HIV vaccine, and have found that theirs can elicit the types of antibodies that are required to provide broad protection against HIV.

What is different with this new vaccine?

Known as bnAbs, the broadly neutralizing antibodies in Wyatt's team's vaccine neutralized multiple HIV strains as they bound onto critical sites on the virus. This is particularly good news as HIV's mutation rate is high and rapid, so being able to bind onto a number of HIV strains is a strong step forward for the vaccine.

The biggest challenge for HIV vaccine designers has been to find ways to stimulate the immune system into creating bnAbs that hit a number of vulnerable sites on the virus. This, in turn, will protect people against a high number of HIV strains. 

The team tested their drug by inoculating 12 HIV-positive rabbits with their vaccine, and then compared their results with a control group that only received a single glycan-shielded version of Env — a glycan shield poses barriers against antibodies. 

The team quickly discovered that their vaccine was much more effective than the single glycan-shielded one, with five of the rabbits developing antibodies that could neutralize a number of HIV isolates. An isolate is a virus carried by an infected person, or animal in this case, rather than when it's grown in a lab. 

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"The finding is an important demonstration that vaccination against HIV if done in the right way, can achieve the goal of inducing bnAbs to multiple sites on the virus," said Wyatt.

The next steps for the team are to carry on testing small animals before hopefully moving onto monkeys, and ultimately, onto humans.

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