PREFERENTIAL ANTIBODY RECOGNITION OF STRUCTURALLY DISTINCT HIV-1 GP120 MOLECULES

We have developed an assay, using a biosensor matrix and surface plasm on resonance, that rapidly and reproducibly measures antibody reactivi ty to human immunodeficiency virus type 1 (HIV-1) gp120 in various str uctural conformations. In particular, antibodies displaying preferenti al reactivity to a CD4-binding competent (''native,'' rgp120) or CD4-b inding incompetent (''reduced,'' rcmgp120) monomeric gp120 molecule we re distinguished. This technique has advantages over conventional enzy me-linked immunosorbent assay (ELISA) methodology in which it is diffi cult to control the concentration of protein adsorbed to the ELISA wel ls and a significant disruption of protein structure occurs on adsorpt ion. A population of gp120 molecules that lacked CD4 receptor binding capacity and bound antibodies specific for reduced gp120 was found in several native gp120 preparations. The relative amount of this CD4-bin ding incompetent population varied among the various preparations stud ied. This presence of CD4-binding incompetent molecules within various native recombinant gp120 preparations may have implications for HIV-1 envelope vaccine development. By measuring antibody-binding ratios, s everal monoclonal antibodies were identified, which, although elicited by immunization with various native gp120 preparations, bound specifi cally to reduced gp120. The ability to screen antibody specificity aga inst HIV-1 envelope proteins with different conformations will assist in determining the quality of antibodies induced by various HIV-1 enve lope vaccine candidates.