Stable expression of red fluorescent protein-blasticidin deaminase fusion gene (rfp-bsd) as a selectable marker for DNA transfection in Babesia ovata.

The red fluorescent protein (rfp)-blasticidin deaminase (bsd) fusion gene was transfected into Babesia ovata by electroporation with the plasmid DNA and selected with 15 µg/mL of blasticidin S under the in vitro culture condition. The transfected parasite with episomal DNA was selected and cultured for further analysis based on the presence of the rfp-bsd fusion gene by PCR and expression of the fusion protein by immunofluorescence antibody test under fluorescence microscopy for 2 months after the transfection. The results are the first, to our knowledge, to demonstrate the expression and stability of the episomal rfp-bsd fusion gene under the control of actin promoter as a selectable marker for the transfection system in B. ovata.