Development and immunogenicity assessment of a DNA launched RNA replicon vaccine candidate against T.cruzi infection

DELFINO, MARÍA ALICIA; TRINITARIO, SEBASTIÁN NICOLÁS; DZVONYK, POLINA; CARDOSO LANDABURU, ALEJANDRO; CERNY, NATACHA; MALCHIODI, EMILIO LUIS; BIVONA, AUGUSTO ERNESTO; TARLETON, RICK L.; SANCHEZ ALBERTI, ANDRÉS

Congreso; XI Congreso de la Sociedad Argentina de Protozoología; 2022

Chagas Disease is a potentially life-threatening illness caused by the protozoan intracellularparasite Trypanosoma cruzi. It affects more than 6 million people worldwide, mainly in LatinAmerica. Currently there is no effective vaccine to prevent or treat this infection. Nucleic acidbased vaccines are efficient type I response inducers and have proven effective to controlintracellular pathogens. Considering this, we have developed a DNA-launched RNA repliconencoding Traspain, a T. cruzi chimeric antigen (DREP-Tp) and assess its immunogenicity in amurine model.Firstly, employing a quality by design approach, an alphavirus-based DREP plasmid wasdeveloped employing in vitro DNA assembly tools. Its identity was confirmed by sequencing andrestriction analysis. Antigen expression was detected by Western blot in transfected HEK293cells lysates.To evaluate its immunogenicity, a murine dose range study was conducted. Groups of C3Hfemale mice were vaccinated by the intramuscular route. Each group received 3 doses of either10 ug, 100 ug or 250 ug of naked DREP-Tp or PBS (placebo group). As benchmark, a group wasimmunized with 10 ug of recombinant Traspain combined with 50 ug of Cyclic-di-AMP adjuvant(CDA).Exploratory bleedings were performed after each dose. Specific antibody titers were evaluatedby ELISA and epitope specific (TEWETGQI+) CD8+ T cells were determined by dextramer staining.Specific antibody titers were detected only in Traspain-CDA group. Flow cytometry analysisshowed that CD8+ TEWETGQI+ cells were present in all immunized mice groups. Percentages ofthese cells resulted similar among all DREP-Tp groups and showed a tendency to be higher thanTraspain-CDA group.In conclusion, a DREP platform was successfully constructed and resulted immunogenic inducinga strong Ag-specific CTL response even at low doses without the inclusion of adjuvants,highlighting its utility as a novel tool for studying the immune response against T. cruzi proteins.