A comparison of biodegradable microparticles and MF59 as systemic adjuvants for recombinant gD from HSV-2.

A recombinant form of glycoprotein D from herpes simplex virus type-2 (gD2) was encapsulated into polylactide-co-glycolide (PLG) microparticles using a previously established solvent evaporation technique. The mean size of the microparticles was about 1 micron and high encapsulation efficiency of the antigen was achieved (70-80%). The microparticles were administered intramuscularly to Balb/C mice and the immune responses were compared with those obtained with the oil in water adjuvant MF59. The serum IgG response to gD2 induced by the microparticles was comparable with that induced by MF59. The serum neutralization titres were also comparable for microparticles and the emulsion. However, the microparticles induced a higher IgG2a isotype response and a more potent serum IFN-gamma response than MF59, suggesting a more Th1 type of response. The MF59 induced higher levels of serum IL-4 and IL-5 cytokines, suggesting a more Th2 type of response.