Use of a staphylococcal superantigen as a tool in novel vaccine designs against Trypanosoma cruzi

SANCHEZ ALBERTI ANDRÉS,; SARRATEA MARÍA BELÉN; MALCHIODI EMILIO LUIS; FERNÁNDEZ LYNCH MARÍA JULIETA; ANTONOGLOU MARÍA BELÉN; BIVONA AUGUSTO; NOLI TRUANT SOFÍA; FERNÁNDEZ MARISA MARIEL

Mar del Plata

Congreso; LXIV Reunión Anual de la SAI; 2016

SAIC-SAI

Chagas disease, caused by the protozoan Trypanosoma cruzi (T. cruzi) affects millions of people worldwide. Despite the efforts, there is still no vaccine to treat or prevent the infection.Superantigens (SAgs) are exotoxins that simultaneously bind MCH-II and TCR in a non-conventional way, inducing a peptide-non-specific proliferation of T lymphocytes and proinflammatory cytokine release. SEG is a type II SAg produced by Staphylococcus aureus.Here we use a SEG mutant N24A, with low affinity for TCR, in combination with the catalytic domain of the major cystein proteinase of T. cruzi Cruzipain (Nt-Cz) in vaccination protocols to evaluate the immune response against the parasite. We also construct a chimeric antigen between the two proteins for its further use in vaccination protocols.SEG N24A and Nt-Cz were produced as recombinant proteins in E.coli. C3H/HeN mice were immunized subcutaneously with five doses of 10 µg of total protein as follows: I-PBS; II-SEG N24A; III-Nt-Cz with CpG-ODN as adjuvant; IV-SEG N24A and Nt-Cz; V-SEG N24A and Nt-Cz with CpG-ODN. 7 days after the last immunization, Nt-Cz-specific serum IgG titers were determined by ELISA and the delayed-type hypersensitivity (DTH) test was performed by intradermal injection of Nt-Cz. Footpad swelling responses were measured 48 hs later.Specific antibody titers against Nt-Cz were detected by groups III, IV and V, showing significant differences against the control group. In the DTH in-vivo assay, there was a positive tendency in the celular immune response for the groups containing Nt-Cz compared with the control group.The chimeric antigen gen was constructed and cloned in prokaryotic and eukaryotic (pcDNA 3.1) expression plasmids. The chimeric protein was produced as a recombinant protein in E. coli.It was purified and recognized by anti-SEG and anti-Nt-Cz antibodies in Western Blot analysis. HEK 293T cells were transiently transfected with the pcDNA 3.1-chimera construction. The protein expression was confirmed by immunofluorescence.These preliminary studies show a potential adjuvant activity of SEG N24A. Its use, in combination with parasite antigens or as a novel chimeric immunogen represents a promising tool for vaccines against T.cruzi.