Humoral and cellular immune responses in BALB/c and C57BL/6 mice immunized with cytoplasmic (CRA) and flagellar (FRA) recombinant repetitive antigens, in acute experimental Trypanosoma cruzi infection

Abstract

In previous studies, cytoplasmic repetitive antigen (CRA) and flagellar repetitive antigen (FRA) proteins induced specific humoral and cellular immune responses in susceptible and resistant mice in the absence of Trypanosoma cruzi infection with a significant induction of the Interferon-gamma (IFN-gamma) production in those animals. In this follow-up paper, the immunostimulatory and protective effects of these proteins were evaluated by immunizing with CRA or FRA antigens, BALB/c and C57BL/6 mice and challenging with a T. cruzi (Y strain). Both proteins induced humoral response with high levels of IgG isotypes as well as cellular immunity with high levels of IFN-gamma when compared to controls. However, the lymphocyte proliferative response was minimal. The survival rate at 30 days post-infection was significant in CRA (60%) or FRA (50%)--immunized BALB/c mice and CRA (83.3%)--immunized C57BL/6 mice. Taken as a whole these findings indicate that CRA and FRA are immunogenic and potentially important for protective immunity.

Chagas disease-specific antigens: characterization of epitopes in CRA/FRA by synthetic peptide mapping and evaluation by ELISA-peptide assay

“…The identification of antigens as strongly reactive linear epitopes and their characterization would permit their localization in protein models, definition of their biophysical properties and analysis of their binding properties with regards to antibody class, capacity, specificity and selectivity. Despite the determination of the RPs CRA and FRA as antigens for diagnostic purposes through various immunological studies [24,27,29,30,43], there are no published data about the number and composition of their epitopes at the amino acid level.…”

Chagas' disease: IgG isotypes against cytoplasmic (CRA) and flagellar (FRA) recombinant repetitive antigens of Trypanosoma cruzi in chronic Chagasic patients

“…Two antigens with these characteristics were used in this study: cytoplasmatic repetitive antigen (CRA), present in evolved forms of the epimastigote and amastigote of T. cruzi, and flagellar repetitive antigen (FRA), present in the epimastigote and trypomastigote forms of the parasite (9,10). The immune response to these antigens has already been studied in mice (11)(12)(13)(14), in their diagnostic potential and to monitor posttreatment cure (15)(16)(17). However, it is not known which isotypes of immunoglobulin G (IgG) are involved in the immune response generated in patients with Chagas' disease in the presence of these recombinant antigens (Ags-Recs).…”

The Repetitive Cytoskeletal Protein H49 of Trypanosoma cruzi Is a Calpain-Like Protein Located at the Flagellum Attachment Zone

“…Several T. cruzi flagellar and cytoskeletal proteins are potent immunogens in humans and have been used as specific diagnostic and prognostic antigens in the serodiagnosis of Chagas' disease [1], [2], [3]. Immunization of mice with purified or semi-purified fractions of T. cruzi cytoskeleton induced high levels of specific humoral and cellular immune responses that protected the mice against a fatal challenge [4], [5], [6].…”