Identification and characterization of interchangeable cross-species functional promoters between Babesia gibsoni and Babesia bovis

The development of transgenic techniques has been reported in many protozoan parasites over the past few years. We recently established a successful transient transfection system for Babesia gibsoni based on Bg 5′-ef-1α promoter. This study investigated 6 homologous and 6 heterologous promoters for B. gibsoni and B. bovis and identified novel interchangeable cross-species functional promoters between B. gibsoni and B. bovis. Ten out of twelve promoters had heterologous promoter function. In particular, Bg 5′-ef-1α and Bg 5′-actin heterologous promoters resulted in a significantly higher luciferase activity than Bb 5′-ef-1α homologous promoter in B. bovis. The present study showed that Bg 5′-actin promoted the highest luciferase activity in both B. gibsoni and B. bovis. The study further indicates that heterologous promoter function widely exists between B. gibsoni and B. bovis. This finding is an important step for future stable transfection construct design and for the production of vaccines based on transfected B. gibsoni and B. bovis parasites.