COMBINATION OF LIVE ATTENUATTED Trypanosoma cruzi PARASITES WITH IFN- gamma EXPRESSING PLASMID AS AN IMMUNIZATION STRATEGY

CECILIA PEREZ BRANDAN; FERNANDO SANCHEZ VALDEZ; RUBEN O. CIMINO; PATRICIO DIOSQUE; MIGUEL ANGEL BASOMBRIO

Congreso; X Congreso de Protozoologia y Enfermedades Parasitarias; 2014

Immunization of mice with live attenuated Trypanosoma cruzi parasites has proven highly immunogenic and protective against acute lethal challenge. It is known that early interferon-gamma (IFN-γ) release by cells of the innate immune system is critical to lead type 1 response able to control intracellular pathogens. Therefore, the aim of the present work is to test whether the co-administration of a plasmid encoding IFN-γ could improve the protection gain through vaccination with live attenuated parasites. For this purpose C57BL/6J mice were immunized with three doses of 5x105 live metacyclic parasites in combination with 50ug of plasmid pCDNA3- IFN-γ or plasmid alone. The immunization regimens were done every 4 weeks either orally or intramuscularly. Thirty days after the last immunization, animals were challenge with highly virulent T. cruzi parasites and parasitemia was recorded weekly. During the immunization period, peripheral blood was taken to determine infection by attenuated parasites. Serum samples as well as spleen cells were collected to determined cytokines expression. Specific anti-T. cruzi antibodies, avidity index and trypanolitic activity was also evaluated in immunized sera. All immunized animals survive challenge with lethal parasites. So far, addition of IFN-γ, at least as administer in our experimental model, does not modified the protection confer by immunization with attenuated parasites alone. This work is supported by Fundacion Florencio Fiorini and ANPCyT.