Author: Nisha Garg

TcG2/TcG4 DNA Vaccine Induces Th1 Immunity Against Acute Trypanosoma cruzi Infection: Adjuvant and Antigenic Effects of Heterologous T. rangeli Booster Immunization

JUAN CARLOS VAZQUEZ CHAGOYAN Nisha Garg Shivali Gupta BERENICE SALGADO JIMENEZ Nandadeva Lokugamage (2019)

Artículo Científico

Background: Chagas cardiomyopathy is caused by Trypanosoma cruzi (Tc). Two antigenic candidates, TcG2 and TcG4, are recognized by antibodies in naturally infected dogs and humans; and these vaccine candidates provided protection from Tc infection in mice and dogs. Trypanosoma rangeli (Tr) is non-pathogenic to mammals and shown to elicit cross-reactive anti-Tc antibodies. In this study, we investigated if fixed Tr (fTr) can further enhance the efficacy of the TcG2/TcG4 DNA vaccine. Methods and Results: C57BL/6 mice were immunized with TcG2/TcG4 DNA vaccine and fTr (delivered as an adjuvant or in prime-boost approach), and challenged with Tc. Serology studies showed that fTr (±quil-A) elicited Tc- and Tr-reactive IgGs that otherwise were not stimulated by TcG2/TcG4 vaccine only, and quil-A had suppressive effects on fTr-induced IgGs. After challenge infection, TcG2/TcG4-vaccinated mice exhibited potent expansion of antigen- and Tc-specific IgGs that were not boosted by fTr±quil-A. Flow cytometry analysis showed that TcG2/TcG4-induced dendritic cells (DC) and macrophages (M0) responded to challenge infection by expression of markers of antigen uptake, processing, and presentation, and production of pro-inflammatory cytokines. TcG2/TcG4-induced CD4+T cells acquired Th1 phenotype and expressed markers that orchestrate adaptive immunity. A fraction of vaccine-induced CD4+T cells exhibited iTreg phenotype responsible for aversion of self-injurious immune responses. Further, TcG2/TcG4-vaccinated mice exhibited potent expansion of poly-functional CD8+T cells with TNF-a/IFN-g production and cytolytic phenotype post-infection. Subsequently, tissue parasites and pathology were hardly detectable in TcG2/TcG4-vaccinated/infected mice. Inclusion of fTr±quil-A had no clear additive effects in improving the Tc-specific adaptive immunity and parasite control than was noted in mice vaccinated with TcG2/TcG4 alone. Non-vaccinated Gupta et al. Vaccine Testing Against T. cruzi mice lacked sufficient activation of Th1 CD4+/CD8+T cells, and exhibited >10-fold higher levels of tissue parasite burden than was noted in vaccinated/infected mice. Conclusion: TcG2/TcG4 vaccine elicits highly effective immunity, and inclusion of fTr is not required to improve the efficacy of DNA vaccine against acute Tc infection in mice.



Trypanosoma cruzi Chagas Disease Recombinant DNA Vaccine T. rangeli immune efficacy MEDICINA Y CIENCIAS DE LA SALUD