Microparticle Vaccines Against Toxoplasma gondii

Abstract

Significant information indicates that future investigations on Toxoplasma vaccine development have to include adjuvants for enhancing protective immunity against Toxoplasma gondii. Especially, safe and effective adjuvants capable of fulfilling Th1-dependent cellmediated immunity appear to be more likely to be allowed to use for anti Toxoplasma vaccine development. Recently, biodegradable and biocompatible polymers, such as poly (lactide-co-glycolide) (PLG) polymers, have been utilized as safe and efficacious adjuvants to encapsulate antigens for producing long-term release microparticle-based vaccines. PLG microencapsulation allows the sustained release of antigens and facilitates antigen uptake via antigen-presenting cells (APCs) to favorably generate Th1 cell-mediated immunity, which is required for the prevention of T. gondii infection. In our recent work, recombinant surface antigens (rSAGs), including rSAG1, rSAG2, and rSAG1/2, have been, respectively, encapsulated with the PLG polymer for production of PLG-encapsulated rSAG1 (PLG-rSAG1), PLG-encapsulated rSAG2 (PLG-rSAG2), or PLG-encapsulated rSAG1/2 (PLG-rSAG1/2) microparticles. This chapter describes adjuvant effect of PLG microparticles, controlled release of PLG microparticles, PLG microparticles-immune system interaction, Toxoplasma SAG-loaded PLG microparticles, protective immunity by Toxoplasma SAG-loaded PLG microparticles, and future prospects. PLG microparticle vaccines would be advantageous for their application in the development of long-lasting vaccines against T. gondii for future use in humans and animals.