Soybean agglutinin coated PLA particles entrapping candidate vaccines induces enhanced primary and sustained secondary antibody response from single point immunization

Polylactide (PLA) polymer particles entrapping diphtheria toxoid (DT) or tetanus toxoid (TT) were formulated with surface coatings of soybean agglutinin to have dendritic cells (DCs) targeting ability through c-type lectin receptors (CLR). It was observed that soybean agglutinin coating resulted in more association of polymer particles with DCs. Immunization with soybean agglutinin coated polymer particles entrapping DT or TT elicited antibody response better than the plain particles entrapping antigens. Both for TT and DT, single point immunization of soybean agglutinin coated polymer particles along with alum resulted in very high antibody titers; much higher than that observed while immunizing with alum adsorbed antigens or admixture of particle entrapped antigens and alum. More interestingly, single point immunization with soybean agglutinin coated polymer particles also elicited very high secondary antibody response which sustained for more than six weeks in mice. Interactions of different polymeric microparticles formulations with DCs correlated with antibody response. Improved primary and sustained secondary antibody response from single point immunization of antigen entrapped soybean agglutinin coated particles was attributed to the N-linked glycan mediated targeting of polymer particles to DCs.