CHARACTERIZATION OF A SOLUBLE, OLIGOMERIC HIV-1 GP160 PROTEIN AS A POTENTIAL IMMUNOGEN

We have assessed the oligomeric structure and antigenic properties of an affinity purified gp160 protein (oligo-gp160) using biosensor techn ology. Sucrose gradient purification analysis identified the existence of tetrameric, dimeric and monomeric forms of the protein. Reactivity to a broad panel of monoclonal antibodies specific for oligomeric gp1 60, discontinuous epitopes within monomeric gp120 and several linear e pitopes within gp120 (V3) and gp41 was demonstrated. International ser a from several countries, where HIV-1 clades A-F are prevalent, includ ing type O from Cameroon, were reactive with oligo-gp160 indicating co nserved antigenic epitopes. Enhanced immunologic reactivity per gp160 molecule was obtained with oligo-gp160 as compared to other current HI V-1(IIIB) subunit monomeric envelope gp120/gp160 immunogens suggesting higher HIV-1 envelope protein mimicry. HIV-1 antibodies from sera dur ing acute HIV-1 infection were detectable by oligo-gp160 prior to dete ction with either a recombinant, monomeric gp120 protein or several co mmercial HIV-1 screening kits suggesting antibodies sensitive to oligo meric gp160 structure may be present earlier in infection. The oligome ric nature of this gp160 protein preparation and high reactivity with divergent mAbs and HIV-1 sera support the use of this protein as an HI V-1 immunogen.