The present invention is directed to the induction and characterization of a humoral immune response targeting "entry-relevant" gp41 structures. In its broadest aspect, the present invention is directed to methods of raising a neutralizing antibody response to a broad spectrum of HIV strains and isolates. The present invention targets particular molecular conformations or structures that occur at the cell surface of HIV during viral entry into host cells. Such a humoral response can be generated in vivo as a prophylactic measure in individuals to reduce or inhibit the ability of HIV to infect uninfected cells in the individual's body. Such a response can also be employed to raise antibodies against "entry relevant" gp41 structures. These antibodies can be employed for therapeutic uses, and as tools for further illuminating the mechanism of HIV cell entry.