Lowell S Kappmeyer, Mathangi Thiagarajan, David R Herndon, Joshua D Ramsay, Elisabet Caler, Appolinaire Djikeng, Joseph J Gillespie, Audrey OT Lau, Eric H Roalson, Joana C Silva, Marta G Silva, Carlos E Suarez, Massaro W Ueti, Vishvanath M Nene, Robert H Mealey, Donald P Knowles, Kelly A Brayton

Transmission of arthropod-borne apicomplexan parasites that cause disease and result in death or persistent infection represents a major challenge to global human and animal health. First described in 1901 as Piroplasma equi, this re-emergent apicomplexan parasite was renamed Babesia equi and subsequently Theileria equi, reflecting an uncertain taxonomy. Understanding mechanisms by which apicomplexan parasites evade immune or chemotherapeutic elimination is required for development of effective vaccines or chemotherapeutics. The continued risk of transmission of T. equi from clinically silent, persistently infected equids impedes the goal of returning the U. S. to non-endemic status. Therefore comparative genomic analysis of T. equi was undertaken to: 1) identify genes contributing to immune evasion and persistence in equid hosts, 2) identify genes involved in PBMC infection biology and 3) define the phylogenetic position of T. equi relative to sequenced apicomplexan parasites.