On Jan. 17, 2025, scientists from Scripps Research Institute reported finding that some HIV vaccination can lead to the production of anti-immune complex antibodies that recognize immune complexes composed of antibodies rather than the HIV virus alone.

They don’t yet know whether this chain reaction, described in hurts or helps the immune system’s ability to fight HIV, but say that understanding it better could lead to improvements in HIV vaccines.

The observation came about when the team was using advanced imaging tools to study how antibodies evolve after multiple HIV vaccine doses. A technique invented by the lab, known as Electron Microscopy-Based Polyclonal Epitope Mapping (EMPEM), lets the researchers see exactly where on the HIV virus antibodies bind.

When they carried out the experiments on blood from animals that had received multiple doses of an experimental HIV vaccine, they discovered something surprising: some of the antibodies were not binding directly to the HIV viral antigen, but to immune molecules on its surface.

The research team planned to continue studying the antibodies, as well as whether similar antibody responses are produced after multiple doses of other vaccines or during natural infection.