Protective Th1 immune responses against chronic toxoplasmosis induced by a protein-protein vaccine combination but not by its DNA-protein counterpart

Vaccine. 2008 Jul 31. [Epub ahead of print]

Protective Th1 immune responses against chronic toxoplasmosis induced by a protein-protein vaccine combination but not by its DNA-protein counterpart

Jongert E, Verhelst D, Abady M, Petersen E, Gargano N.

Laboratory for Toxoplasmosis, Pasteur Institute of Brussels, Scientific Institute of Public Health, Brussels, Belgium.

Vaccine-induced protection against toxoplasmosis is correlated with cellular immune responses to Toxoplasma gondii, both in animals and man. The goal of the current study was to evaluate whether the combination of a recombinant protein and a plasmid DNA vaccine could offer an advantage over the protein mixture, and protect outbred mice against infection with T. gondii. To this purpose, the chimeric protein rEC2, encoding antigenic fragments of surface-associated proteins MIC2, MIC3 and SAG1, was combined with pGRA7 plasmid DNA or rGRA7 protein. High levels of antibodies were elicited by both vaccine formulations. The protein-DNA vaccine elicited a polarized Th1/Th2 immune response, characterized by IFN-gamma and IL-10, and afforded low protection (24%) against brain cyst formation. In contrast, the protein-protein vaccine elicited a Th1-focused immune response, characterized by IFN-gamma and IL-2 production, conferring a strong protection (79%) against brain cyst formation in chronic toxoplasmosis. We show here that GERBU adjuvanted protein vaccines confer better protection against toxoplasmosis than the protein-DNA heterologous vaccine.

PMID: 18675872 [PubMed - as supplied by publisher]