Development of a microsphere-based immunoassay for the serological diagnosis of equine trypanosomosis

Abstract

Trypanozoon infections in equids are caused by three parasite species in the Trypanozoon subgenus: Trypanosoma equiperdum, T. brucei and T. evansi. They are respectively responsible for infectious diseases dourine, nagana and surra. Due to the threat that Trypanozoon infection represents for international horse trading, accurate diagnostic tests are crucial. Current tests suffer from poor sensitivity and specificity, due in the first case to the transient presence of parasites in the blood and in the second, to antigenic cross-reactivity among Trypanozoon subspecies. This study was designed to develop a microsphere‐based immunoassay for diagnosing equine trypanosomosis. We tested beads coated with eight Trypanosoma spp. recombinant antigens: enolase, GM6, PFR1, PFR2, ISG65, VSGat, RoTat1.2 and JN2118HU. Of these, GM6 was identified as the best candidate for the serological diagnosis of Trypanozoon infections in equids. Using a receiver operating characteristic (ROC) analysis on 349 equine sera, anti-GM6 antibodies were detected with an AUC value of 0.994 offering a sensitivity of 97.9% and a specificity of 96.0%. Our findings show that the GM6 antigen is a good target for diagnosing equine trypanosomosis using a microsphere‐based immunoassay. This promising assay could be a useful alternative to the official diagnostic tool for equine trypanosomosis.

Analysis of Trypanosoma equiperdum Recombinant Proteins for the Serological Diagnosis of Dourine

“…Diagnostic application of this protein should be further investigated by testing a higher number of sera. Regarding use of i-ELISAs, performances of this technique may be improved by utilising chemiluminescent substrates [ 29 ]; however, this requires suitable microplate readers.…”

European Inter-Laboratory Proficiency Test for Dourine Antibody Detection Using the Complement Fixation Test

“…The development of field sample banks would make it possible to determine precise detection thresholds on the basis of tangible biological data from infected animals rather than immunised animals; this would, in turn, maximise sensitivity without excessively reducing specificity. By creating such a bio-bank, it would also be possible to provide full field validation, according to the principles and methods applied to the validation of diagnostic assays for infectious diseases recommended by WOAH, for promising alternatives such as ELISA tests [27,28], Luminex [29] or ICT [30]. More generally, this study highlights the importance for any laboratory carrying out or wishing to carry out CFTs, whether for dourine or any other disease, to participate in external performance evaluation processes such as ILPTs in order to guarantee the maintenance of the laboratory's performance.…”

Development of a Test System Based on Recombinant GM6 Antigen from Trypanosoma evansi for the Determination of Surra in Horses

“…They also found a high similarity in the amino acid sequences of GM6 among different trypanosome species, indicating nearly identical antigens. Consequently, GM6-based diagnostic methods not only have potential for diagnosing Surra in equines but also hold utility in epidemiological studies and diagnosing Dourine disease Verney et al (2022). identified 12 false positive sera, with five sera from endemic areas of Northern Argentina testing positive for equine infectious anaemia and West Nile virus, potentially leading to cross-reactivity.…”