T- and B-lymphocyte responses to human immunodeficiency virus (HIV) type 1 in macaques immunized with hybrid HIV/hepatitis B surface antigen particles.

Recombinant human immunodeficiency virus (HIV)/hepatitis B surface antigen (HBsAg) subviral particles of dual antigenicity and immunogenicity were obtained by fusing 84 amino acids of the HIV type 1 external envelope glycoprotein within the pre-S2 part of the hepatitis B middle protein (M.-L. Michel, M. Mancini, E. Sobczak, V. Favier, D. Guétard, E.-M. Bahraoui, and P. Tiollais, Proc. Natl. Acad. Sci. USA 85:7957-7961, 1988). We now describe the humoral and cellular immune response of rhesus monkeys immunized with these hybrid particles. Macaque antisera raised by subcutaneous injections of the HIV/HBsAg particles were shown to be specific for HIV in peptide-binding assays. Moreover, we were able to generate in these vaccinated animals a T-cell-proliferative response to both parts of the hybrid particle, i.e., HIV and HBsAg. These results establish the presence of a T-cell epitope in this HIV segment, which has been shown previously (L.A. Lasky, G. Nakamura, D. H. Smith, C. Fennie, C. Shimasaki, E. Patzer, P. Berman, T. Gregory, and D. J. Capon, Cell 50:975-985, 1987) to be an important domain involved in the binding of the virus to its cellular receptor, the CD4 molecule. This work demonstrates the feasibility of using the HBsAg subviral particle as a carrier protein for the presentation of foreign immunogenic epitopes to the immune system.