Postexposure immunoprophylaxis of primary isolates by an antibody to HIV receptor complex

mAb B4 is a monoclonal antibody directed against HIV receptor complex. The antibody had broad neutralizing activity against HIV and provided postexpos ure prophylaxis to hu-peripheral blood leukocyte (PBL)-severe combined immu nodeficient mice and chimpanzees. B4 recognized a complex receptor site for HIV on the T cell surface that includes CD4 and also may be influenced by interaction with HIV coreceptors. mAb B4 preferentially neutralized primary HIV-1 isolates compared with T cell line-adapted strains, including syncyt ium-inducing and non-syncytium-inducing phenotypes, representatives from HI V-1 subtypes A-G, as well as HIV-2, simian immunodeficiency virus, and chim eric simian/human immunodeficiency virus (SHIV). Neutralization was demonst rated in both pre- and postinfection models. The administration of mAb B4 a fter infectious challenge totally interrupted the infection of hu-PBL-sever e combined immunodeficient mice by PBL-grown HIV-1 and the infection of chi mpanzees by chimp-adapted HIV-1. This mode of protection suggested that the anti-HIV receptor antibody is efficacious for prophylaxis after exposure t o HIV and for prevention of maternal transmission and may be an effective a ntiretroviral agent for treatment.