Identification of highly conserved Trypanosoma cruzi antigens for the development of a universal serological diagnostic assay

Abstract

Chagas Disease is an important neglected tropical disease caused by Trypanosoma cruzi . There is no gold standard for diagnosis and commercial serological tests perform poorly in certain locations. By aligning T. cruzi genomes covering parasite genetic and geographic diversity, we identified highly conserved proteins that could serve as universal antigens for improved diagnosis. Their antigenicity was tested in high-density peptide microarrays using well-characterized plasma samples, including samples presenting true infections but discordant serology. Individual and combination of epitopes were also evaluated in peptide-ELISAs. We identified >1400 highly conserved T. cruzi proteins evaluated in microarrays. Remarkably, T. cruzi positive controls had a different epitope recognition profile compared to serologically discordant samples. In particular, multiple T. cruzi antigens used in current tests and their strain-variants, and novel epitopes thought to be broadly antigenic failed to be recognized by discordant samples. Nonetheless, >2000 epitopes specifically recognized by IgGs from both positive controls and discordant samples were identified. Evaluation of selected peptides in ELISA further illustrated the extensive variation in antibody profiles among subjects and a peptide combination could outperform a commercial ELISA, increasing assay sensitivity from 52.3% to 72.7%. Individual variation in antibody profiles rather than T. cruzi diversity appears to be the main factor driving differences in serological diagnostic performance according to geography, which will be important to further elucidate. ELISA with a combination of peptides recognized by a greater number of individuals could better capture infections, and further development may lead to an optimal antigen mixture for a universal diagnostic assay.

In vitro diagnostic methods of Chagas disease in the clinical laboratory: a scoping review

“…Despite the differences, the overall performance is comparable, especially among the commercial kits, which are still available to this date. Moreover, DTU genetic diversity may not be responsible for disagreements between serological tests, and rather may be more to individual variation in antibodies’ profiles ( Majeau et al, 2024 ).…”

Molecular similarities between the genes for Trypanosoma cruzi microtubule associated proteins, mammalian interferons, and TRIMs

“…511633.79)(Ibañez et al 1988), showed 76% sensitivity in 61 samples of infected sera(Mucci et al 2017). It is therefore conserved in a majority of strains of T. cruzi and can perhaps be used universally where Chagas' disease testing is necessary(Negrette et al 2008;Majeau et al 2024). 6% identical, and IFN-γ was 17.9% identical.…”