Therapeutic effects of vaccine derived from amastigote surface protein-2 (ASP-2) against Chagas disease in mouse liver.

This study investigated the efficacy of the vaccine in liver of mice infected with the Trypanosoma cruzi (T. cruzi) and immunized with AdASP-2. For this purpose, histopathological analysis and gene expression of COX-2, TNF-alpha, TNFR, iNOS, cytochrome C, caspase-3, TLR4, IL-6 and IL10 were evaluated. The following groups were used in this study: Group 1 - Control Group (CTRL) animals received AdβGal vehicle; Group 2 - Infected Group (TC) animals were infected with T. cruzi; Group 3 - Immunized Group (AdASP-2): animals were immunized by AdASP-2 vaccine; Group 4 - Immunized and Infected Group (AdASP-2+TC) animals were infected with T. cruzi and immunized by AdSP-2 vaccine. A significant decrease of amastigote nests was noticed in the group of animals that were immunized with AdASP-2 and infected on the same day. COX-2 and TNF-alpha gene expressions increased in TC group, whereas TNF-alpha decreased in the TC+AdASP-2 group. TNFR expression was high in AdASP-2+TC group. iNOS expression was high for all experimental groups whereas cytochrome C decreased for all experimental groups. Caspase 3 increased in TC and TC+AdASP-2 groups. The gene expression of TLR4 and IL-10 showed an increase in AdASP-2+TC group. Finally, hepatic fibrosis was noticed to TC and AdASP-2 + TC groups. Taken together, our results demonstrated that vaccination with AdASP-2 was effective against the acute phase of experimental Chagas disease as a result of a more powerful and rapid immune response closely related to expression of some inflammatory genes, such as iNOS, TNF-alpha, TLR 4, and IL-10.