Immune-potentiation of Pneumococcal Capsular Polysaccharide Antigen using Albumin Microparticles

Abstract

Microparticles (MPs) offer several advantages as unique vaccine delivery system, including the ease to manufacture, targeted delivery of antigen payload, sustained antigen release and possible role as an immuneadjuvant. In this study, we evaluated albumin matrix for pneumococcal (Pnc) serotype specific capsular polysaccharide (PS) antigen MPs. Microencapsulation of Pnc PS was successful with a product yield of >72%. The MP size, 1-5 μm, and negative zeta potential (-26.5 mV) were optimized to ensure effective -uptake and presentation of Pnc PS antigens to immune cells. In mice, ST 19F and 23F MPs exhibited >10-fold increase (P<0.01) in ST specific IgG response over PS in solution given with or without alum. Relatively higher immune response was observed for ST 6B MPs when compared to PS solution; however, ST6B PS solution along with alum resulted in an overall higher response when compared to ST6B MPs. Microencapsulation may offer a simple and effective mechanism for the immune-enhancement of poorly immunogenic antigens such as Pnc PS.