IMMUNE SYSTEM, HIV-1, ANTIBODY, GP120, B13, ENVELOPE GLYCAN PROTEIN, CD4- BINDING SITE, AIDS, APOPTOSIS, CELL MEMBRANE, CLEAVAGE ON PAIR OF BASIC RESIDUES, COILED COIL, DISULFIDE BOND, ENVELOPE PROTEIN, FUSION PROTEIN, HOST-VIRUS INTERACTION, MEMBRANE, TRANSMEMBRANE, VIRAL IMMUNOEVASION, VIRION CRYSTAL STRUCTURE OF HIV-GP120 CORE IN COMPLEX WITH CD4- BINDING SITE ANTIBODY B13, SPACE GROUP C222 3IDX