Antibodies are proteins that are part of the immune system. 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 strains of HIV. Scientists can learn a lot about preventing HIV infection in studies using these broadly neutralizing antibodies. There are two different ways that these antibodies can be given to people. Both methods for giving people antibodies have been tested and found to be safe for other diseases.