Streptococcus equi antigens adsorbed onto surface modified poly-ɛ-caprolactone microspheres induce humoral and cellular specific immune responses

Streptococcus equi subsp. equi is the causative agent of Strangles, which is one of the most costly and widespread infectious diseases, affecting the respiratory tract of Equidae. In this work, polyvinyl alcohol, alginate and chitosan were used in formulations of surface modified poly-ɛ-caprolactone microspheres which were evaluated after adsorption of S.equi enzymatic extract for physicochemical characteristics and in vivo immune responses in mice. After subcutaneous immunisation, the formulations induced higher lymphokines levels, in accordance with cellular and humoral immune responses, as compared to the free antigen, successfully activating the paths leading to Th1 and Th2 cells. The obtained results highlight the role of these microspheres as an adjuvant and their use to protect animals against strangles.