Induction of homologous virus neutralizing antibodies in guinea-pigs immunized with two human immunodeficiency virus type 1 glycoprotein gp120-iscom preparations. A comparison with other adjuvant systems.

The immunogenicity in guinea-pigs of the human immunodeficiency virus type 1 envelope glycoprotein gp120 in immune stimulating complex (iscom) was compared to that of gp120 adjuvanted with QuilA-matrix (iscom without attached antigen), aluminium hydroxide (alum) and the Ribi adjuvant system. Gp120 was either incorporated into iscoms by covalent conjugation (iscom(c)) or by acid treatment of gp120 (iscom(a) and both these preparations induced high ELISA antibody titres to gp120. Virus neutralizing (VN) antibodies were most frequently induced by gp120 in iscom(c), iscom(a) or in alum and correlated to high titres to the V3-region of gp120. Further, antibodies induced by gp120-iscom(c) most efficiently inhibited binding of a VN monoclonal antibody GP13 to the CD4 binding region of gp120 whereas gp120-iscom(a) induced the highest mean titre of antibodies blocking the binding of [125I]gp120 to CD4. These results suggest that the gp120-iscom preparations efficiently induced high levels of gp120 specific antibodies and that the adjuvant formulation of gp120 affect the specificity and functional properties of elicited antibodies.