Induction of partial protection against infection with Toxoplasma gondii genotype II by DNA vaccination with recombinant chimeric tachyzoite antigens

• DOI: 10.1016/j.vaccine.2009.02.058
• Publication Date: 2009-02-25T10:35:12Z
• Authors: Carina Rosenberg; Stéphane De Craeye; Erik Jongert; Nicola Gargano; Elisa Beghetto; Paola Del Porto; Thomas Vorup-Jensen; Eskild Petersen
• Keywords: Protozoan Vaccines; 0301 basic medicine; Mice, Inbred BALB C; Genotype; Recombinant Fusion Proteins; Vaccination; Antibodies, Protozoan; Antigens, Protozoan; cellular immunity; dna vaccination; toxoplasma gondii; 3. Good health; Mice; 03 medical and health sciences; Toxoplasmosis, Animal; Vaccines, DNA; Animals; Cytokines; Humans; Female; Toxoplasma

Infection with the obligate intracellular parasite Toxoplasma gondii is a significant source of parasitic infections worldwide. In adults, infections may often lead to severe retinochoroiditis. Infection of the foetus causes abortion or congenital pathology that may lead to neurological complications. Although several strategies have been suggested for making a vaccine, none is currently available. Here, we investigate the protection conferred by DNA vaccination with two constructs, pcEC2 (MIC2-MIC3-SAG1) and pcEC3 (GRA3-GRA7-M2AP), encoding chimeric proteins containing multiple antigenic sequences from T. gondii. After challenge with a T. gondii genotype II, but not a genotype III strain, a significant decrease in cerebral cyst load was found compared to the controls. The immune protection involved a cell-mediated immune response with the synthesis of the cytokines IFN-? and IL-10. In silico structure analysis and the expression profile of EC2, suggest an association between antigen stability, the degree of protein secondary structure and induction of cellular immune responses. Intracellular protein degradation is an important step in the pathway leading to presentation of antigenic peptides on Major Histocompatibility Complex molecules. We suggest that degradation of this chimeric protein may have contributed to the induction of a cellular immune response via enhanced presentation of antigenic peptides on Major Histocompatibility Complex class I molecules.