Proteomic Selection of Immunodiagnostic Antigens for Trypanosoma congolense

Jennifer R Fleming,Thomas W M Crozier,Lalitha Sastry,Lauren Sullivan,Grant B Napier,Michael A J Ferguson,Armando Jardim

doi:10.1371/journal.pntd.0002936

Abstract

Animal African Trypanosomosis (AAT) presents a severe problem for agricultural development in sub-Saharan Africa. It is caused by several trypanosome species and current means of diagnosis are expensive and impractical for field use. Our aim was to discover antigens for the detection of antibodies to Trypanosoma congolense, one of the main causative agents of AAT. We took a proteomic approach to identify potential immunodiagnostic parasite protein antigens. One hundred and thirteen proteins were identified which were selectively recognized by infected cattle sera. These were assessed for likelihood of recombinant protein expression in E. coli and fifteen were successfully expressed and assessed for their immunodiagnostic potential by ELISA using pooled pre- and post-infection cattle sera. Three proteins, members of the invariant surface glycoprotein (ISG) family, performed favorably and were then assessed using individual cattle sera. One antigen, Tc38630, evaluated blind with 77 randomized cattle sera in an ELISA assay gave sensitivity and specificity performances of 87.2% and 97.4%, respectively. Cattle immunoreactivity to this antigen diminished significantly following drug-cure, a feature helpful for monitoring the efficacy of drug treatment.

Highlights

Animal African Trypanosomosis (AAT) presents a severe problem for agricultural development in sub-Saharan Africa
Animal African Trypanosomosis (AAT) is a set of diseases whereby animals are infected with single-cell parasites that replicate in their bloodstream
One of the principal trypanosome species responsible for AAT in cattle is Trypanosoma congolense and, there are drug-treatments for these infections, current diagnostic methods are impractical for field use

Summary

Introduction

Animal African Trypanosomosis (AAT) presents a severe problem for agricultural development in sub-Saharan Africa. The economic loss in cattle production is estimated to be between US$ 1 billion per annum [1,2,3], increasing to US$ 5 billion when secondary costs are taken into consideration [1,3,4]. It is estimated that around 60 million cattle are at risk in endemic regions [1,4]. AAT affects many other domestic livestock such as pigs, camels, goats, sheep and horses. There are no vaccines and treatment is usually via intramuscular administration using trypanocides, either diminazene (therapeutically) or isometamidium (prophylactically). Current diagnostics methods are laborious (microscopy), expensive (PCR) and generally impractical for use in the field, at the point of treatment

Objectives

Methods

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Discussion

Conclusion