mRNA Shot Triggers Potent HIV-Blocking Antibodies in Early Study

Researchers have reported that a messenger-RNA-based vaccine reliably induced broadly neutralizing antibodies against HIV in both human volunteers and rhesus macaques, overcoming a technical hurdle that has frustrated vaccine developers for decades. Two peer-reviewed studies published in Science Translational Medicine on 30 July describe how shielding a normally exposed segment of the virus’s envelope protein prevented the immune system from being distracted, sharply improving the quality of the antibody response. In a Phase 1 trial, 80% of recipients who got the modified vaccine produced antibodies that blocked HIV infection in laboratory tests, compared with just 4% when the decoy segment of the viral surface was left visible. The same design also protected monkeys from a simian-human immunodeficiency virus challenge, the papers report. The candidate shot, which uses the same mRNA platform deployed in Covid-19 vaccines, was generally safe and well tolerated. About 6.5% of participants developed transient hives that resolved with antihistamines, and investigators are examining ways to minimise the reaction in future studies. The findings mark one of the most encouraging advances yet toward a preventive HIV vaccine, though larger and longer-term trials will be needed to confirm durability and real-world efficacy.