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

DELFINO MA; TRINITARIO SN; DZVONYK P; CARDOSO A; CERNY N; MALCHIODI EL; BIVONA AE; TARLETON RL ; SÁNCHEZ ALBERTI A

Mendoza

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

Sociedad Argentina de Protozoología

Chagas Disease is a potentially life-threatening illness caused by theprotozoan intracellular parasite Trypanosoma cruzi. It affects more than6 million people worldwide, mainly in Latin America. Currently there is noeffective vaccine to prevent or treat this infection. Nucleic acid-based vaccinesare efficient type I response inducers and have proven effective to controlintracellular pathogens. Considering this, we have developed a DNA-launched RNAreplicon encoding Traspain, a T. cruzi chimeric antigen (DREP-Tp) and assessits immunogenicity in a murine model.Firstly, employing a quality by design approach, an alphavirus-based DREPplasmid was developed employing in vitro DNA assembly tools. Its identity wasconfirmed by sequencing and restriction analysis. Antigen expression wasdetected by Western blot in transfected HEK293 cells lysates.Then, to evaluate its immunogenicity, a murine dose range study wasconducted. 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-Tpor PBS (placebo group). As benchmark, a group was immunized with 10 ug of recombinantTraspain combined with 50 ug of Cyclic-di-AMP adjuvant (CDA). Exploratory bleedings were performed after each dose. Specific antibodytiters were evaluated by ELISA and epitope specific (TEWETGQI+) CD8+ T cells weredetermined by dextramer staining.Specific antibody titers were detected only in Traspain-CDA group. Flowcytometry analysis showed that CD8+ TEWETGQI+ cells were present in allimmunized mice groups. Percentages of these cells resulted similar among allDREP-Tp groups and showed a tendency to be higher than Traspain-CDA group.In conclusion, a DREP platform was successfully constructed and resultedimmunogenic inducing a strong Ag-specific CTL response even at low doseswithout the inclusion of adjuvants, highlighting its utility as a novel toolfor studying the immune response against T.cruzi proteins.