Toxoplasma gondii: chimeric Dr fimbriae as a recombinant vaccine against toxoplasmosis

Toxoplasma gondii is responsible for fetopathy in farm animals and humans and severe disease in immunocompromised individuals (i.e. AIDS patients). Effective vaccines, inducing protective and long-lasting immunity to this global parasite, are still desired. In the work, we evaluated the immunogenic and immunoprotective activity of Escherichia coli chimeric Dr fimbriae bearing selected antigenic epitopes of three T. gondii antigens (SAG1, GRA1 and MAG1), in comparison with conventional recombinant antigens obtained in E. coli expression system. Our data demonstrate a very high protective efficacy of recombinant antigens supplemented with Freund's adjuvants, whereas chimeric Dr fimbriae as a vaccine proved non-protective. The recombinant antigen vaccine induced a strong specific antibody response and prevented the brain cysts formation by 89%. The results are promising and should be confirmed in further study on farm animals by use of less aggressive than Freund's adjuvant preparations.