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

DELFINO MARIA ALICIA; TRINITARIO SN 1,2,3, DZVONYK P 2,3, CARDOSO A 1,2,3, CERNY N 1,2, MALCHIODI EL, BIVONA AE ; TARLETON RL; SANCHEZ ALBERTI ANDRES

Mendoza

Congreso; Congreso Sociedad Argentina de Parasitologia; 2022

Sociedad Argentina de Parasitologia

Chagas Disease is a potentially life-threatening illness caused by the protozoan intracellular parasite Trypanosoma cruzi. It affects more than 6 million people worldwide, mainly in Latin America. Currently there is no effective vaccine to prevent or treat this infection. Nucleic acid-based vaccines are efficient type I response inducers and have proven effective to control intracellular pathogens. Considering this, we have developed a DNA-launched RNA replicon encoding Traspain, a T. cruzi chimeric antigen (DREP-Tp) and assess its immunogenicity in a murine model.Firstly, employing a quality by design approach, an alphavirus-based DREP plasmid was developed employing in vitro DNA assembly tools. Its identity was confirmed by sequencing and restriction analysis. Antigen expression was detected by Western blot in transfected HEK293 cells lysates.Then, to evaluate its immunogenicity, a murine dose range study was conducted. Groups of C3H female mice were vaccinated by the intramuscular route. Each group received 3 doses of either 10 ug, 100 ug or 250 ug of naked DREP-Tp or PBS (placebo group). As benchmark, a group was immunized 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 evaluated by 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 analysis showed that CD8+ TEWETGQI+ cells were present in all immunized mice groups. Percentages of these cells resulted similar among all DREP-Tp groups and showed a tendency to be higher than Traspain-CDA group.In conclusion, a DREP platform was successfully constructed and resulted immunogenic inducing a 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.