Development of an immunoassay for the differential diagnosis of trypanosomosis of veterinary interest: A preliminary proteomic survey of Trypanosoma evansi trypomastigotes using lc/ms/ms approach for differential diagnostics

Abstract

The veterinary trypanosomes Trypanosoma evansi and Trypanosoma vivax are parasites that affect many animals species such as horses, camels and bovines causing significant economic losses to livestock industry around the world. Recently, human cases have been described. In Brazil, outbreaks of these parasites have been reported in several states from north to south. The differential diagnosis is not efficient and there is no differential field test to be used. Thus using the proteomic approach, we began the study of proteins differentially expressed in each of the parasites. The aim of this study is to identify proteins expressed by T. evansi trypomastigotes in mouse experimental infections, with emphasis in the identification of potential drug targets and differential diagnostic antigens. In a preliminary proteomic survey using LC/MS/MS, 33 proteins from T. evansi trypomastigotes were identified and assigned to COG functional groups, with most of them belonging to the group of cellular processes and signaling and metabolism proteins. Among the identified proteins there were cyclophilin and cysteine peptidase, which have been described as virulence factors and potential drug targets in other trypanosomatids, for being involved in parasite growth and survival in mammalian hosts. Furthermore, we identified several glycolytic enzymes, such as ATP-dependent phosphofructokinase, enolase and glycosomal fructose-bisphosphate aldolase. In T. evansi these enzymes are especially important for flagellar movement, a process that is dependent of the environmental glucose concentration. Considering that flagellar movement is essential for parasite infection, glycolitic enzymes also become attractive targets for future studies on their drug target potential. The T. evansi proteomic survey will also be extended with the analysis of more trypomastigote samples by both LC/MS/MS and 2DE-MALDI-MS/MS, in order to provide a comprehensive coverage of the repertoire of proteins expressed by this stage of the parasite. For the identification of antigenic proteins with potential for use in “surra” immunodiagnosis, we will also perform 2DE-immunoblots with sera from animals infected with T. evansi trypomastigotes.