RECOMBINANT TCP21 AS POTENTIAL ADJUVANT FOR TRYPANOSOMA CRUZI VACCINES BASED ON LIVE ATTENUATED PARASITES

CECILIA PEREZ BRANDAN; ANDREA C. MESIAS; THAISE LARA TEIXEIRA; CLAUDIO VIEIRA DA SILVA

Santa Fe

Congreso; XXVIII Reunión Anual de la Sociedad Argentina de Protozoología y Enfermedades Parasitarias; 2016

Sociedad Argentina de Protozoologia

In the last years, vaccine research against Trypanosoma cruzi has gained renew attention due, mainly, to the advances in vaccine technology and to economic models predicting that a therapeutic or prophylactic vaccine would be useful as an additional tool to control Chagas Disease in endemic areas. Several parasite antigens as well as DNA plasmids administered alone or in recombinant bacteria or virus as a delivery system have been evaluated showing promising results for further vaccine development. TcP21 is a ubiquitous secreted protein of T. cruzi and its role during parasite cell invasion is not completely understood yet. However, recombinant TcP21 promotes parasite cell invasion and acts as a phagocytosis inducer by activating actin polymerization. Our goal was to study the immunogenicity and protective efficacy of the recombinant protein TcP21 in a mouse model of T. cruzi infection. For this purpose groups of mice were intraperitoneally vaccinated with the recombinant protein emulsified in saponin, given alone or in combination with live attenuated parasites, which have already demonstrated to induce a strong protective effect. Three weeks later, mice were given a similar booster vaccine. Four weeks after the last immunization, animals were challenge with a lethal dose of T. cruzi parasites. During the immunization period sera samples were collected for parasite specific IgGs and IgGs subtypes quantification and cytokines detection. Spleen was removed for lymphocytes isolation and further proliferation assays and cytokine production determination. After challenge, parasite load was recorded twice a week. Our results showed that when administered alone, recombinant TcP21 does not confer protection against a lethal challenge; however, when TcP21 is formulated with live attenuated parasites the protective capacity seems to be improved compared to the one obtained by immunization with live attenuated parasite alone. So far these results create the impression that recombinant TcP21 per se is not a good inducer of a protective response, nevertheless its incipient adjuvant properties leave the possibility to further evaluate this protein in view of generating new multicomponent vaccine formulations. This work is supported by Agencia Nacional de Promoción Científica y Técnica.