BIODEGRADABLE MICROPARTICLES WITH AN ENTRAPPED BRANCHED OCTAMERIC PEPTIDE AS A CONTROLLED-RELEASE HIV-1 VACCINE

Polyactide-co-glycolide microparticles, with an entrapped branched oct americ peptide from human immunodeficiency virus (HIV-1), were prepare d by a solvent evaporation method. The microparticles were characteriz ed for size distribution, antigen loading level, and integrity. Mice i n one group were each immunized with a single dose of a controlled-rel ease microparticle formulation containing 300 mu g of peptide and the serum IgG responses to the antigen were compared with those of mice fr om a second group that were immunized at 0, 4, and 26 weeks with 100-m u g doses of the same peptide immunogen adsorbed to alum. The controll ed-release microparticles induced an antibody response comparable to t hat from the alum-immunized group. The subcutaneous and the intramuscu lar routes of administration were compared in additional groups of mic e for the microparticles, and both routes induced similar responses. A suspending vehicle for the microparticles was also evaluated and did not affect the immunogenicity of the controlled-release formulation co ntaining both small and large microparticles, although the immunogenic ity of smaller microparticles immunized alone was affected.