An experimental HIV vaccine induced broadly neutralizing antibodies at least among a small group of volunteers in a Phase 1 study, suggesting that a two-dose regimen of this vaccine, given eight weeks apart, can elicit immune responses against HIV.
This is according to a study – “Vaccination induces HIV broadly neutralizing antibody precursors in humans” by David J. Leggat, Kristen W. Cohen, Jordan R. Willis, et al – that appeared in the journal Science.
The vaccine, called eOD-GT8 60mer, is germline-targeting – i.e. it was designed to induce the production of broadly neutralizing antibodies by targeting and stimulating the right antibody-producing cells. This vaccine induced broadly neutralizing antibodies in 97% (or all but one) of 36 recipients.
Antibodies are proteins made by the immune system to help fight infections. Broadly neutralizing antibodies have been shown to neutralize many genetic variants of HIV, but thus far, they have been difficult to elicit by vaccination.
“Learning how to induce broadly neutralizing antibodies against pathogens with high antigenic diversity, such as HIV, influenza, hepatitis C virus, or the family of betacoronaviruses, represents a grand challenge for rational vaccine design,” stated the researchers from Scripps Research, Fred Hutchinson Cancer Center, National Institutes of Health and other institutions in the US and Sweden.. “Germline-targeting vaccine design offers one potential strategy to meet this challenge.”
The Phase 1 clinical trial is part of the International AIDS Vaccine Initiative that was started in 2018 to evaluate the safety of eOD-GT8 60mer and the immune responses it induces. This trial included 48 adults aged 18 to 50.
Eighteen of the participants received a 20-microgram dose of the vaccine and, eight weeks later, a same-size dose of the vaccine with an adjuvant. Another 18 received a 100-microgram dose of the vaccine and, eight weeks later, a same-size dose of the vaccine with an adjuvant. Twelve, meanwhile, received two doses of a saline placebo, eight weeks apart.
The adjuvant – called AS01B – was developed by the pharmaceutical company GSK. The vaccines and placebo were given into the arm muscle.
The researchers found:
- all vaccine recipients but no placebo recipients were found to produce antibodies elicited by the eOD-GT8 60mer vaccine
- vaccine-induced responses increased after the second vaccination
- no serious adverse events reported among the study participants
- no participants acquired HIV infection during the study
Another Phase 1 study on this vaccine candidate is underway.
Related to this study, there are still questions in need of being answered – e.g. how long the elicited antibodies from the first immunization last. But with over 38 million people living with HIV or AIDS around the globe, finding a vaccine – aside from a cure – is a priority, and to date, over 20 HIV vaccine clinical trials are ongoing around the world, according to the International AIDS Vaccine Initiative.
And by showing that broadly neutralizing antibodies can be induced by a vaccine, the new study was cited for helping “inform the development of other types of immunizations, not just HIV vaccines.”
