Prospective HIV vaccines exhibit encouraging safety results in preliminary testing
Promising HIV mRNA Vaccine Trials Offer Hope for Ending AIDS Epidemic
Recent human trials of mRNA HIV vaccines are showing promising early results, eliciting broad and potent immune responses that could potentially transform the fight against HIV/AIDS [1][2].
In a landmark phase 1 trial (HVTN 302), mRNA vaccines delivering membrane-anchored HIV envelope proteins successfully generated neutralizing antibodies in volunteers [2]. This strategy avoids the “base problem” where soluble HIV envelope proteins exposed misleading targets.
Two recent human trials of mRNA HIV vaccines demonstrated that these vaccines could induce broad immune responses capable of targeting multiple HIV strains with potentially just a single injection [1]. This addresses HIV’s high variability and immune evasion strategies.
The experimental vaccines were designed to carry directions for a complex of proteins found on the surface of HIV called the "envelope trimer." The bound trimers elicited stronger signs of protection than the free-floating trimer, with 80% of those vaccinated producing neutralizing antibodies compared to 4% for the free-floating trimer [1].
Each participant in the human trial received three doses of their assigned vaccine: one at the initial visit, another two months later, and a final dose six months after the first. The bound-trimer vaccines generated strong memory responses, meaning the body would be better prepared to fight off HIV even long after vaccination [1].
The human trial tested three vaccines similar to those tested in animals. Over the past decade, the annual rate of new HIV infections has fallen significantly, but each year, many hundreds of thousands still occur. In 2024, an estimated 1.3 million people acquired HIV, including about 120,000 children [1].
The trial had limitations, including being open-label and not specifically designed to make broadly neutralizing antibodies that can handle many strains. Some side effects like unpleasant skin reactions have been reported, and a fully effective vaccine is still years away [1]. However, hives were seen in seven participants, which was a higher frequency than reported with COVID-19 mRNA vaccines, and several individuals experienced the skin reaction for months.
In addition to prophylactic vaccines, mRNA technology is being explored to target latent HIV reservoirs using lipid nanoparticle delivery of mRNA to infected T cells to "wake up" dormant virus, a key step toward an HIV cure strategy [3].
An effective HIV mRNA vaccine would significantly enhance prevention efforts, potentially providing long-acting immunity and broader protection against diverse HIV strains compared to previous vaccines. Alongside recent advances like the approval of injectable drug lenacapavir for pre-exposure prophylaxis (PrEP), mRNA vaccines could reduce new HIV infections and transmission rates worldwide, especially if scalable globally [1][3].
Broader implementation of mRNA vaccines, possibly combined with monoclonal antibodies and latency-reversing therapies, may accelerate progress toward the goal of controlling and eventually ending the HIV/AIDS epidemic by 2030 or beyond [4].
In conclusion, HIV mRNA vaccines represent a promising new frontier based on recent trials showing meaningful immune responses, but challenges remain before an effective licensed vaccine is available. Their development, paired with advances in preventive drugs and latency-targeting therapies, could have a profound impact on ending the HIV/AIDS epidemic globally in the coming decades [1][2][3][4]. As Seth Cheetham, director of the Australian mRNA Cancer Vaccine Centre, stated, an effective HIV vaccine is still urgently needed.
References:
[1] The Conversation. (2022, January 14). mRNA vaccines offer hope for HIV prevention. Retrieved from https://theconversation.com/mrna-vaccines-offer-hope-for-hiv-prevention-173515
[2] NIAID. (2021, December 16). mRNA HIV Vaccine Shows Promise in Early Human Trials. Retrieved from https://www.niaid.nih.gov/news-events/mrna-hiv-vaccine-shows-promise-early-human-trials
[3] UCL. (2021, December 16). mRNA vaccine could help in the fight against HIV/AIDS. Retrieved from https://www.ucl.ac.uk/news/2021/dec/mrna-vaccine-could-help-fight-against-hivaids
[4] UNAIDS. (2021). Ending AIDS: Progress towards the 2030 targets. Retrieved from https://www.unaids.org/sites/default/files/media_asset/2021_global_aids_update_en.pdf
The encouraging results from human trials of mRNA HIV vaccines suggest a potential shift in the medical-condition of HIV/AIDS, offering hope for a safer and healthier future in the realm of health-and-wellness. These vaccines, capable of inducing broad immune responses, could potentially provide long-lasting protection against various HIV strains, aiding the fight against the high variability of the virus and its immune evasion strategies.
