Engineered HIV vaccine coaxes primate immune systems into rare broadly neutralizing antibodies

Researchers at the La Jolla Institute for Immunology, Scripps Research, and IAVI report an HIV vaccine that, in rhesus macaques, produced the strongest HIV-fighting antibody response yet seen in primates. Published in Nature, the work is the payoff of a 14-year collaboration and tackles the core reason HIV has resisted vaccines: the virus hides behind a shifting coat of sugar molecules, mutates rapidly, and changes shape on infection, so B cells almost never get the chance to refine effective antibodies. The rare people who do produce ‘broadly neutralizing’ antibodies — which lock onto conserved viral structures even as the rest of the virus mutates — became the template the team tried to reproduce on demand.

The approach, called germline targeting, works by engineering vaccine molecules that mimic key sites on HIV’s envelope protein and delivering them as a priming shot followed by a series of ‘shepherding’ boosters. Each step is designed to walk a naive B cell, step by step, from its untrained state toward producing broadly neutralizing antibodies. Roughly 44 percent of the animals went on to make these antibodies in abundance, and they closely resembled the antibodies found in the rare humans who generate their own — a signal the researchers read as evidence the strategy may translate even better to people.

The study did not test whether the antibodies actually block infection, and the team wants to push the response rate well above 44 percent by tuning the booster regimen. Still, the priming immunogen has already been evaluated in humans (HVTN 144) and is in a Phase 1 trial (IAVI G004), with plans underway to test the full regimen in a future human study.