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ARS Home » Pacific West Area » Pullman, Washington » Animal Disease Research » Research » Publications at this Location » Publication #282813
Title: Repertoire of theileria equi antigens bound by equine antibody during persistent phase of infection

Author
item Gomes Da Silva, Marta
item GRACA, T - Washington State University
item Suarez, Carlos
item Knowles Jr, Donald

Submitted to: Molecular and Biochemical Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/2013
Publication Date: 3/26/2013
Citation: Gomes Da Silva, M., Graca, T., Suarez, C.E., Knowles Jr, D.P. 2013. Repertoire of theileria equi antigens bound by equine antibody during persistent phase of infection. Molecular and Biochemical Parasitology. 188(2):109-115.

Interpretive Summary: Theileriosis in horses and cattle is a hemoprotozoan disease caused by T. equi that is transmitted by ticks, and causes death or persists for the lifespan in their respective hosts. Due to transmission risk associated with persistence, infection severely limits movement of horses and cattle between countries, resulting in enormous economic losses. Recent re-emergence of infections of horses in the United States has increased concern relative to this parasite. The aim of this study was the identification of T. equi merozoite antigens that are recognized by antibodies in horses infected with distinct T. equi strains. Previously studies had shown that equine post-infection serum consistently recognized at least five T. equi merozoite antigens, but their precise identity remained unknown. To determine specificity of antibody target identification, mainly three different techniques were applied: immunoaffinity chromatography, two-dimensional electrophoresis gels and liquid chromatography tandem mass spectrometry (LC-MS/MS). The analysis of the data obtained by LC-MS/MS using T. equi genome database, allowed the identification of five T. equi merozoite antigens included Equi Merozoite Antigen-2 (EMA-2), EMA-3 and EMA-4, a previously uncharacterized protein annotated as “signal peptide containing protein”, and the 40S ribosomal protein S12.

Technical Abstract: Theileriosis in horses and cattle is caused by tick-borne Apicomplexa parasites that cause death or persist for life in their respective hosts. Due to transmission risk associated with persistence, infection severely limits movement of horses and cattle between countries. The recent reemergence of Theileria equi infection in U.S. horses demonstrates the continual threat these Apicomplexa parasites represent to global animal health. A paucity of data concerning equine immune responses to T. equi, including antigens recognized by antibodies in clinically asymptomatic, chronically infected horses, precludes vaccine development. Therefore, this investigation was initiated to detail the repertoire of the equine antibody responses to T. equi during chronic infection. This was accomplished by defining T. equi merozoite antigens that are recognized by antibodies in horses infected with distinct T. equi strains. Previously it was shown that equine post-infection serum consistently recognized at least five T. equi merozoite antigens, but their precise identity remained unknown. To determine specificity of antibody target identification, T. equi merozoite antigens were first isolated using equine post-infection serum by affinity chromatography. Proteins recognized by the equine antibodies were then isolated from two-dimensional electrophoresis gels, and analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) using the recently available T. equi genome database. The five T. equi antigens identified included Equi Merozoite Antigen-2 (EMA-2), EMA-3 and EMA-4, a previously uncharacterized protein annotated as “signal peptide containing protein”, and the 40S ribosomal protein S12.