Trypanosoma equiperdum Low Molecular Weight Proteins As Candidates for Specific Serological Diagnosis of Dourine

Abstract

The diagnosis of dourine can be difficult because the clinical signs of this disease in horses are similar to those of surra, caused by Trypanosoma evansi. Moreover, T. equiperdum and T. evansi are closely related and, so far, they cannot be distinguished using serological tests. In a previous work, the T. equiperdum protein pattern recognized by antibodies from dourine-infected horses and the humoral immune response kinetics were investigated by immunoblotting assay; a total of 20 sera from naturally and experimentally infected horses and from healthy animals were tested. Immunoblotting analysis showed that antibodies from infected horses specifically bind T. equiperdum low molecular weight proteins (from 16 to 35 kDa), which are not recognized by antibodies from uninfected horses. In this work, we tested other 615 sera (7 from naturally infected horses and 608 sera from healthy horses and donkeys): results confirmed the data obtained previously. In addition, six SDS-PAGE bands with molecular weight ranging from 10 to 37 kDa were analyzed by mass spectrometry, in order to identify immunogenic proteins that could be used as biomarkers for the diagnosis of dourine. A total of 167 proteins were identified. Among them, 37 were found unique for T. equiperdum. Twenty-four of them could represent possible candidate diagnostic antigens for the development of serological tests specific for T. equiperdum.

Humoral immune response and delayed-type hypersensitivity in rabbits infected with Trypanosoma equiperdum

“…Moreover, immunoblotting results obtained in the present work demonstrated that antibodies from infected rabbits, in contrast to antibodies from healthy rabbits, specifically recognise a T. equiperdum antigenic profile with low molecular weight bands (< 37 kDa), just as observed in dourine positive horses 22,23 . These results seem to confirm the hypothesis that T. equiperdum low molecular proteins are important in the humoral immunitary response against this pathogen both in horse and rabbit and could represent possible candidate diagnostic antigens for the development of more specific tests for dourine.…”

“…The gradual increase in the number and intensity of protein bands recognized by rabbit positive sera during the time, has been already described for horse positive sera in Luciani et al 22,23 .…”

“…). Sera reacting with PP = OD Sample−OD Negative Control / OD Positive Control−OD Negative Control ×100www.nature.com/scientificreports/ bands with molecular weight (MW) equal or less than 37 kDa were considered as positive for Trypanosoma antibodies22,23 .…”

Equine trypanosomosis: enigmas and diagnostic challenges

“…Since this VSG accounts for 10% of the protein content of a bloodstream form trypomastigote, it is a major, yet undefined, component of crude antigen preparations for IFAT and ELISA. Other proteins in crude trypanosome antigen preparations may cross-react with antibodies unrelated to infection with trypanosomes [72].…”

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