Prime-boost immunization with recombinant cruzipain co-administered with MALP as adjuvant raises a protective immune response and decreases tissue injury in experimental T.cruzi infection

FRANK FM,; CAZORLA SI,; BECKER PD; CORRAL RS; MALCHIODI EL,; GUZMAN CA

Rio do Janeiro, Brasil

Congreso; IMMUNO RIO 2007. 13th International Congress of Immunology.; 2007

We have demonstrated that native Cruzipain (Cz) plus CpG-oligodeoxynucleotide is able to induce immunoprotection against Chagas disease. To optimize Cz-based vaccination, we prepared a recombinant Cz antigen and evaluated its immunogenicity when co-administered with different adjuvants (CpG-ODN and MALP, a TLR2/6 agonist never tested as enhancer of anti-parasite immunity) by intranasal (in) and intradermal (id) routes. Mice were immunized with GI: PBS; GII: rCz id; GIII: rCz id prime + [  rCz+MALP in] boost; GIV: [rCz+CpG] id. All immunized mice displayed increased specific IgG titers [GIV (6.82 ± 0.8 x 106) > GII (46933 ± 42667) > GIII (12800 ± 28622)]. A strong cellular immune response was detected in GIII by both DTH and lymphoproliferative assays (p<0.001). Splenocytes from GIII and GIV mice released significantly (p<0.05) enhanced levels of IFN-g (198 ±95 and 812 ± 230 pg/ml, respectively) as quantified by ELISA. ELISPOT analysis of LTCD4+-depleted splenocytes revealed that GIII mice showed the highest frequency (8.0 ± 1.6) of IFN-ã-producing cells. After inoculating a lethal dose of trypomastigotes, GIII presented a significant decrease in parasitemia levels and 60% survival, while the remaining mice died between 14-27 dpi. In other groups infected sublethally, the activity of serum CPK, LDH and ASAT (as enzyme markers of muscle injury) was determined at 100 dpi. Results were significantly (p<0.05) lower in GIII in coincidence with histopathologic findings. We conclude that a prime-boost immunization regimen combining rCz with MALP adjuvant constitutes a successful strategy to immunoprotect against murine Chagas disease.