Germline-Targeting HIV Vaccine Elicits Broadly Neutralizing Antibodies in 44% of Primates, Nature Study Finds
A Scripps Research and La Jolla Institute for Immunology vaccine guided rhesus macaques to produce broadly neutralizing HIV antibodies, with human trials already underway.
Editor's Note ·
- Correction:
- The article states the IAVI G004 trial "began dosing participants in January 2026." The cited IAVI press release states that the first doses were actually administered on December 15, 2025, at the Perinatal HIV Research Unit in Soweto, South Africa; January 6, 2026 is the date IAVI's press release announcing that milestone was published, not the dosing date itself. Dosing in IAVI G004 began in December 2025.
- Clarification:
- lji.org and iavi.org are not on the project's source_allowlist. Both are the actual primary research institutions behind this study (La Jolla Institute for Immunology, a nonprofit immunology research institute, and IAVI, a global nonprofit HIV vaccine research organization); all claims attributed to them were verified verbatim against their snapshots during review. Adding lji.org and iavi.org to config/source_allowlist.txt is recommended.
Overview
An experimental HIV vaccine designed to walk the immune system through a step-by-step training process succeeded in generating broadly neutralizing antibodies in a substantial share of vaccinated primates, according to a study published in Nature on June 30, 2026. The vaccine, developed by researchers at Scripps Research and the La Jolla Institute for Immunology (LJI) working with IAVI, produced detectable broadly neutralizing antibody activity in the blood of roughly 44 percent of tested animals, according to both the Nature paper and an LJI news release.
What We Know
The vaccine follows an approach called “germline targeting,” so named because, according to LJI, it “targets naive B cells in their ‘germline’ or naive form, before they begin their training process.” Rather than a single shot, the regimen unfolds in stages: researchers “first administered a ‘priming’ vaccine meant to activate each animal’s naive B cells,” and the animals “then received a series of ‘shepherding’ booster shots to help their B cells develop along the right path,” LJI reported.
The goal is to coax the immune system toward producing broadly neutralizing antibodies, a category of antibodies that, as News-Medical explained, “can actually bind to HIV and recognize key viral structures, even if the rest of the virus mutates.” That mutation problem is central to why an HIV vaccine has eluded researchers for decades: “the worldwide diversity of HIV mutations is extraordinary,” News-Medical noted, and “even the diversity within one individual person living with HIV is dramatic.”
The study, led by LJI Professor and Chief Scientific Officer Shane Crotty, Ph.D., and Scripps Research professor William Schief, Ph.D., with co-first authors Jon Steichen, Ph.D. (Scripps Research) and Patrick Madden, Ph.D. (LJI Instructor), tested the vaccine in rhesus macaques at the Emory National Primate Research Center, per LJI. The Nature paper states that “serum bnAb activity developed in 44% of animals,” while broadly neutralizing antibody lineages — an earlier stage of the immune response — were generated in “≥50% of animals,” with neutralization breadth reaching “67% compared to the reference bnAb” in some cases, according to the paper’s abstract.
“This feels like a huge success,” Crotty said, according to LJI. “We succeeded in taking ultra-rare antibody responses and turning them into common responses by the end of the vaccination process,” he added.
Human Trials Already Underway
Components of the same germline-targeting strategy are already being tested in people. LJI reported that “the priming immunogen used in this study was evaluated in humans in the HVTN 144 trial and is currently being tested in the Phase 1 trial IAVI G004.” That trial, which IAVI announced began dosing participants in January 2026, is evaluating three immunogens — eOD-GT8 60mer, Core-g28v2 60mer, and N332-GT5 gp151 — delivered via Moderna’s mRNA platform in 96 healthy adult participants across six South African clinical sites. According to IAVI, G004 “builds on the promising results observed in the IAVI G001, G002, and G003 clinical trials, which demonstrated proof of concept for a biological pathway to generate bnAbs against HIV.”
“It is very exciting to see the launch of the IAVI G004 clinical trial. With this year’s global funding cuts to HIV prevention, care, and treatment, bringing new prevention tools forward is more important than ever,” said Mark Feinberg, IAVI’s president and CEO, in the same release. Schief, describing the trial’s goals, said IAVI and its partners are “excited to evaluate these mRNA immunogens at lower doses, including two immunogens previously tested at higher doses and the first-in-human test of our N332-GT5 membrane-bound trimer.”
Looking beyond G004, News-Medical reported that “IAVI, Scripps Research, the HIV Vaccine Trials Network, and partners are now advancing plans to further evaluate the full immunization regimen in a future human clinical study” — meaning the complete prime-and-shepherding-boost sequence tested in the primate study, not just its individual components, has yet to be tried in people.
What We Don’t Know
The primate study demonstrates that the vaccine can reliably induce broadly neutralizing antibody responses under laboratory conditions; it does not by itself establish that vaccinated animals, or eventually vaccinated people, are protected from HIV infection. The current human trials, including G004, are still evaluating safety, dosing, and individual immunogen components rather than the complete regimen, and no timeline has been given for when a full-regimen human efficacy trial might begin. Neither the paper nor the accompanying releases specify the total number of primates enrolled in the study.