Antibodies are proteins that are part of the immune system, made by the B cells that are part of the white blood cells. Antibodies are specific for each different foreign “invader,” such as flu, measles, or chickenpox. For example, an HIV antibody will not recognize or work against the flu virus. In fact, most HIV antibodies are very specific for one strain of HIV and maybe a few close relatives.

Researchers have found that some people have rare HIV antibodies, called broadly neutralizing antibodies, which work against many different global strains of HIV. Scientists can learn a lot about preventing HIV in studies using these broadly neutralizing antibodies, or bnAbs for short (pronounced bee-nabs). BnAbs can also be made in the lab using the same techniques used to manufacture medications. Giving people antibodies through infusions into a vein and through injections have been tested and found to be safe for other diseases. Earlier studies done by the HVTN have proven that bnAbs can be protective against some strains of HIV, but the single bnAb alone was not strong enough to fully protect people. Now we are testing combinations of 3 bnAbs to try to improve the protection and provide coverage against more strains of HIV.