Characterization and Diagnostic Application of Trypanosoma cruzi Trypomastigote Excreted-Secreted Antigens Shed in Extracellular Vesicles Released from Infected Mammalian Cells

Abstract

Chagas disease, caused by Trypanosoma cruzi, although endemic in many parts of Central and South America, is emerging as a global health threat through the potential contamination of blood supplies. Consequently, in the absence of a gold standard assay for the diagnosis of Chagas disease, additional antigens or strategies are needed. A proteomic analysis of the trypomastigote excreted-secreted antigens (TESA) associated with exosomal vesicles shed by T. cruzi identified ϳ80 parasite proteins, with the majority being trans-sialidases. Mass spectrometry analysis of immunoprecipitation products performed using Chagas immune sera showed a marked enrichment in a subset of TESA proteins. Of particular relevance for diagnostic applications were the retrotransposon hot spot (RHS) proteins, which are absent in Leishmania spp., parasites that often confound diagnosis of Chagas disease. Interestingly, serological screens using recombinant RHS showed a robust immunoreactivity with sera from patients with clinical stages of Chagas ranging from asymptomatic to advance cardiomyopathy and this immunoreactivity was comparable to that of crude TESA. More importantly, no cross-reactivity with RHS was detected with sera from patients with malaria, leishmaniasis, toxoplasmosis, or African sleeping sickness, making this protein an attractive reagent for diagnosis of Chagas disease.

Proteomics and Leishmaniasis: Potential Clinical Applications

“…The identification of secreted proteins has potential applications in diagnosis of parasitic diseases. Proteomic analysis of T. cruzi EVs identified 80 proteins, including trans‐sialidases, mucins and mucin‐associated surface proteins, GP63, and retrotransposon hot spot proteins . Retrotransposon hot spot reacted with sera from chagasic patients in different stages of the disease, but not with sera from patients with malaria, leishmaniasis, African trypanosomiasis or toxoplasmosis, indicating high specificity .…”

“…Proteomic analysis of T. cruzi EVs identified 80 proteins, including trans‐sialidases, mucins and mucin‐associated surface proteins, GP63, and retrotransposon hot spot proteins . Retrotransposon hot spot reacted with sera from chagasic patients in different stages of the disease, but not with sera from patients with malaria, leishmaniasis, African trypanosomiasis or toxoplasmosis, indicating high specificity . A recent study analyzed immunoreactive proteins secreted by Leishmania that could be applied to the diagnosis of leishmaniasis .…”

Extracellular vesicles as mediators of immunopathology in infectious diseases

“…About 80 parasite proteins, essentially trans‐sialidases, were identified. Sera from patients with clinical stages of Chagas disease showed a clear immunoreactivity for exosome associated TESA, and no cross‐reactivity was seen with sera from patients with malaria, leishmaniasis, toxoplasmosis, or African sleeping sickness, making this protein an attractive reagent for diagnosis of Chagas disease …”

The protein family TcTASV-C is a novel Trypanosoma cruzi virulence factor secreted in extracellular vesicles by trypomastigotes and highly expressed in bloodstream forms

“…Although TcTASV-C proteins are not major components of the parasite in trypomastigotes derived from in vitro cultured cells [ 10 ], several TcTASV-C peptides have been recently identified in secretomes of T . cruzi trypomastigotes [ 14 – 16 ]. Interestingly, TcTASV peptides were found in the bloodstream trypomastigote proteome, but not in proteomes from in vitro cultured cell derived trypomastigotes [ 17 ].…”