Development of a stable transgenic Theileria equi parasite expressing an enhanced green fluorescent protein/blasticidin S deaminase

Sci Rep. 2021 Apr 27;11(1):9107. doi: 10.1038/s41598-021-88594-w.


Theileria equi, an intraerythrocytic protozoan parasite, causes equine piroplasmosis, a disease which negatively impacts the global horse industry. Genetic manipulation is one of the research tools under development as a control method for protozoan parasites, but this technique needs to be established for T. equi. Herein, we report on the first development of a stable transgenic T. equi line expressing enhanced green fluorescent protein/blasticidin S deaminase (eGFP/BSD). To express the exogenous fusion gene in T. equi, regulatory regions of the elongation factor-1 alpha (ef-1α) gene were identified in T. equi. An eGFP/BSD-expression cassette containing the ef-1α gene promoter and terminator regions was constructed and integrated into the T. equi genome. On day 9 post-transfection, blasticidin-resistant T. equi emerged. In the clonal line of T. equi obtained by limiting dilution, integration of the eGFP/BSD-expression cassette was confirmed in the designated B-locus of the ef-1α gene via PCR and Southern blot analyses. Parasitaemia dynamics between the transgenic and parental T. equi lines were comparable in vitro. The eGFP/BSD-expressing transgenic T. equi and the methodology used to generate it offer new opportunities for better understanding of T. equi biology, with the add-on possibility of discovering effective control methods against equine piroplasmosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aminohydrolases / genetics*
  • Gene Expression Regulation
  • Green Fluorescent Proteins / genetics*
  • Nucleosides / pharmacology
  • Organisms, Genetically Modified*
  • Peptide Elongation Factor 1 / genetics
  • Plasmids
  • Theileria / drug effects
  • Theileria / genetics*
  • Transfection


  • Nucleosides
  • Peptide Elongation Factor 1
  • enhanced green fluorescent protein
  • Green Fluorescent Proteins
  • blasticidin S
  • Aminohydrolases
  • blasticidin S deaminase