Leading areas of research include genetics, individual variations in the immune response and exposure to or infection by less deadly HIV variants. The ability to stimulate immune responses is called immunogenicity . These products, custom-made proteins known as antibodies , circulate in body fluids, primarily blood and lymph. Several different antibodies can be generated. So-called binding antibodies simply attach to part of HIV and may or may not have antiviral effects.
Functional antibodies are binding antibodies that actually do something more.
Scientists have identified the outer envelope of HIV as important for stimulating neutralizing antibodies. The chief regulatory T cell, the helper T cell , also is HIV's main target. The virus attaches to the cell through a receptor on the cell's surface called CD4 . A subset of helper T cells, memory T cells , are evoked on first exposure to an invading organism. If the virus enters the body again, memory T cells will quickly stir the immune system into action.