Story at a glance
- Researchers gave participants the vaccine or a placebo in a phase 1 clinical trial of the HIV vaccine candidate.
- Participants were able to produce the targeted B cells in response to the vaccine.
- This vaccine could be the first stage in a multi-step vaccine regimen for HIV.
Human immunodeficiency virus (HIV) is a virus that attacks the body’s immune system. Over time, this can lead to Acquired Immunodeficiency Syndrome, or AIDS. Advances in treatment of HIV using antiviral drugs has been successful in recent years, but producing a vaccine has been elusive. Scientists at the International AIDS Vaccine Initiative (IAVI) and Scripps Research have been working on an approach that is proving to be fruitful so far.
The goal of the researchers was to introduce a vaccine that induces the production of broadly neutralizing antibodies, or bnAbs. These antibodies are able to attach to a wide variety of HIV strains, hence why it is called broadly neutralizing. But to do this, they need to target rare immune cells called naive B cells. This vaccine is meant to be the first part of a multi-step vaccine regimen to elicit many types of bnAbs.
In the phase 1 clinical trial, there were 48 HIV negative participants, according to a fact sheet. Participants either received two doses of vaccine or placebo, spaced apart by two months. The participants were also split into low- and high- dose groups. Out of the participants who received the vaccine, 97 percent had detectable levels of the target immune cell. The researchers think that these levels were “high enough to be considered promising for boosting as a next step,” according to the fact sheet. Participants were monitored for 12 months after vaccination, and there were no safety concerns.
All told, it seems like the vaccine has done what it was meant to do.
“We and others postulated many years ago that in order to induce bnAbs, you must start the process by triggering the right B cells — cells that have special properties giving them potential to develop into bnAb-secreting cells,” says William Schief, a professor and immunologist at Scripps Research and executive director of vaccine design at IAVI’s Neutralizing Antibody Center (NAC), the laboratory that developed the vaccine, in a press release.
“In this trial, the targeted cells were only about one in a million of all naïve B cells. To get the right antibody response, we first need to prime the right B cells. The data from this trial affirms the ability of the vaccine immunogen to do this.”
If the data are correct and the following phases of clinical trials go well, this could be a gamechanger in preventing HIV infection.
“Given the urgent need for an HIV vaccine to rein in the global epidemic, we think these results will have broad implications for HIV vaccine researchers as they decide which scientific directions to pursue,” says Mark Feinberg, president and CEO of IAVI.
“This is a tremendous achievement for vaccine science as a whole,” says Dennis Burton, professor at Scripps Research, scientific director of the IAVI Neutralizing Antibody Center and director of the NIH Consortium for HIV/AIDS Vaccine Development.
The group plans to launch further trials for the vaccine, according to the fact sheet. There are also plans to work with Moderna to create an mRNA version of the vaccine that aims to induce the same B cells.
Experts are hopeful that this approach to HIV vaccines will also be helpful for other pathogens, like influenza virus, dengue virus, Zika virus, hepatitis C viruses and the malaria parasite.
“This clinical trial has shown that we can drive immune responses in predictable ways to make new and better vaccines, and not just for HIV,” Burton said. “We believe this type of vaccine engineering can be applied more broadly, bringing about a new day in vaccinology.”
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