Development and characterization of a formulation based covalent conjugation with polyacrylic acid and recombinant major surface antigen (SAG1) of Toxoplasma gondii

Introduction: Toxoplasmosis is a major disease caused by Toxoplasma gondii that infects approximately half the world's population. The development of an effective vaccine would be extremely valuable for preventing disease. SAG1 is a major surface antigen of parasites and one of the most antigenic proteins of T. gondii. Developing highly antigenic and effective vaccine formulations using new generations of adjuvants and delivery systems is very important. Polyacrylic acid (PAA) is a polymer that increases the immunogenicity of an antigen to which it is covalently linked. The aim of this study was to develop a new formulation candidate with high stability and immunogenicity potential against toxoplasmosis via a covalent conjugation of PAA and the SAG1 protein. Methods: PAA and SAG1 were covalently conjugated using a water-soluble carbodiimide crosslinker that activates carboxyl groups for spontaneous reaction with primary amines. To demonstrate conjugation of these molecules in size exclusion chromatography (SEC), fluorescence spectroscopy was used. Results: For the first time, one of the most important surface antigens of T. gondii was conjugated to a PAA polymer, SEC and fluorescence spectra results. Discussion and conclusion: The obtained SAG1-PAA conjugate can be used for vaccine development against T. gondii in future.