An early study for an experimental HIV vaccine has shown promising results.
97% of recipients in a phase 1 study showed immune system activity in response to the vaccine.
But there is still a long way to go and there is no guarantee that this vaccine will prevent HIV infection.
An HIV vaccine candidate is showing positive initial results, stimulating a critical component of the human immune response in 97% of vaccine recipients.
It was a small phase 1 study testing a vaccine that was made from an engineered version of a protein that exists on the HIV virus. This particle was designed to prime the body to generate broadly neutralizing antibodies, which are thought to be key to building immunity against HIV. Broadly neutralizing antibodies would recognize a broad range of HIV subtypes, which is necessary to provide immunity because the HIV virus mutates frequently.
Forty-eight participants received either the vaccine candidate or a placebo, and 35 of 36 of those given the vaccine candidate showed activation of B-cell precursors of broadly neutralizing antibodies that could produce the first step toward immunity. The crux of this technique is essentially to train the immune system to recognize a broad range of naturally occurring HIV subtypes, according to William Schief, one of the study’s authors. Schief is a professor in the department of immunology and microbiology at Scripps Research.
“There are just a few spots on the surface of the HIV spike that stay the same or relatively the same between different isolates. And we’re trying to get very specific antibodies that have very specific properties that allow them to bind to those exact spots,” he said Schief.
In the phase 1 study, no one reported any serious side effects, and other side effects such as injection site pain or headache were mild to moderate and resolved in one to two days.
These are the results, published in the academic journal Science on 1 December 2022, World AIDS Day, were first announced in 2021 at a virtual conference hosted by the International AIDS Society HIV Research for Prevention. The trial was co-managed by the International AIDS Vaccine Initiative and Scripps Research.
Researchers have been trying to create an HIV vaccine for nearly 40 years
HIV is notoriously difficult to vaccinate against. Part of this is due to HIV’s tendency to mutate. Evolving and changing rapidly, it can avoid the immune system making itself more difficult to recognize.
Furthermore, virtually no one, apart from a few high-profile cases, has been cured of an HIV infection. This means that we don’t know which types of immune cells in the body can actually protect against infection.
Theoretically, this vaccine will be the first in a series of multiple injections, each of which uses a different HIV particle to train the immune system. As the shots progress, the molecules get closer and closer to those of real HIV viruses, until the antibodies produced can bind to many different types of HIV.
“It’s kind of a whole new way to think about how to make a vaccine,” Schief said.
Moderna is developing its own HIV vaccine based on similar research
According to Schief, his team is currently working with biotech giant Moderna to develop and test a vaccine to deliver the HIV particles that train the immune system via mRNA, instead of the protein-based model this most recent study uses. A Phase 1 study is currently testing the same particle, as well as another engineered particle, with an mRNA delivery system. Another study is testing the same particle in a clinical trial in Africa.
It will take some time before Phase 2 trials can begin, according to Schief, and there’s no guarantee the vaccine will ultimately work.
But if it does, this technique could be used to make other vaccines, he said, such as a universal coronavirus or flu vaccine.
“We’re optimistic that there’s some chance this approach could be helpful for more than just HIV,” Schief said, “although if it just helped HIV that would be huge.”
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