The main function of the immune system is to protect individuals from infective micro-organisms by producing specific antibodies and activating cells specialised in recognising and eliminating the infective agent and its products. The antibodies can prevent viruses from entering cells by recognising and binding to specific molecules on the surfaces of cells and viruses but, for reasons that are still unknown, this does not happen in the case of AIDS because the functions of the immune system are impaired and the virus manages to get the upper hand. The research being carried out at the HIV Immunobiology Unit has the aim of studying humoral immunity as a possible means of developing new AIDS vaccines and therapies.