HIV Vaccine Tests in Primates Point to the Potential for Future Developments

By: Marcus J. Hopkins, Health Policy Lead Consultant, ADAP Advocacy

Research published in Nature found that germline-targeting vaccines administered in primates were the first to generate high numbers of ‘broadly neutralizing ' virus-fighting antibodies against HIV (Steichen et al., 2026).

Source: Nature

This vaccine, a collaboration between La Jolla Institute for Immunology and Scripps Research, works by trying to find rare naïve B cells (white blood cells, also called lymphocytes), and using a series of booster shots to get them to produce “broadly neutralizing antibodies” (bnAbs). Using 24 rhesus macaques split into four groups of six, Steichen et al. produced bnAb lineages in at least 50% of the animals, with individual antibodies reaching up to 67% of the neutralization breadth of the human BG18 antibody.

This practice, commonly referred to as “germline targeting,” essentially preempts the vaccine virus by creating antibodies that could provide between 50% and 90% protection against HIV transmission.

And “could” is the primary word here:

While Steichen et al. attempted to find these rare B cells and get them to produce the desired antibodies, they did not actually test the efficacy of these antibodies in any scientific, clinical, or real-world setting. This means that, while this is an exciting scientific breakthrough, there is little evidence that any near-term vaccines will be developed using this process, in no small part because successfully identifying and targeting these very rare B cells (which are, admittedly, rarer in humans than rhesus macaques) is both incredibly difficult and very much a trial-and-error process that seems to be reliant upon individual animal genetics.

Exciting news, to be certain.

Source: CDC

In many ways, however, Pre-Exposure Prophylaxis (PrEP) provides similar prevention efficacy, with Yeztugo (Gilead Sciences) showing up to 100% efficacy in biological females in one trial and 96% in a second, primarily male drug-trial cohort (Patel et al., 2025).

While PrEP is not a vaccine regimen, it does provide excellent protection against the acquisition of HIV! 

The development of an HIV vaccine presents significant challenges due to the virus's rapid mutations, its ability to integrate into the host's DNA, and its mechanisms for evading the immune response. Conventional vaccines function by training the immune system to identify consistent pathogen features. In contrast, HIV employs strategies that counter this approach. Although research from the La Jolla Institute demonstrates potential, it remains, under specific circumstances, the most recent effort aimed at eradicating HIV.

Disclaimer: All funders of the ADAP Advocacy Association are publicly listed on our website. 

Disclaimer: Guest blogs do not necessarily reflect the views of the ADAP Advocacy Association; rather, they provide a neutral platform for the author to promote open, honest discussion of public health-related issues and updates.

References:

[1] Patel, R. R., Hoover, K. W., Lale, A., Cabrales, J., Byrd, K. M., & Kourtis, A. P. (2025, September 18). Clinical Recommendation for the Use of Injectable Lenacapavir as HIV Preexposure Prophylaxis — United States, 2025. MMWR, 74(35), 541-540 https://www.cdc.gov/mmwr/volumes/74/wr/mm7435a1.htm

[2] Steichen, J. M., Madden, P. J., Flynn, C. T., Phulera, S., Shil, M., Kalyuzhniy, O., Liguori, A., Kifude, C., Sewall, L. M., Cottrell, C. A., Ma, K. M., Baboo, S., Diedrich, J. K., McKenney, K., deCamp, A. C., Carnathan, D. G., Phung, I., Ramezani-Rad, P., Marina-Zárate, E., Freeman, B., … Schief, W. R. (2026, June 30). Vaccination elicits HIV broadly neutralizing antibodies in primates. Nature, 656, 723-733. https://doi.org/10.1038/s41586-026-10837-5