The factors involved in gain or loss of virulence in Babesia bovis are unknown. Spherical body protein 2 truncated copy 11 (sbp2t11) transcripts in B. bovis were recently reported to be a marker of attenuation for B. bovis strains. Increased cytoadhesion of B. bovis-infected red blood cells (iRBC) to vascular endothelial cells is associated with severe disease outcomes and an indicator of parasite virulence. Here, we created a stable B. bovis transfected line over-expressing sbp2t11 to determine whether up-regulation of sbp2t11 is associated with changes in cytoadhesion. This line was designated sbp2t11up and five B. bovis clonal lines were derived from the sbp2t11up line by limiting dilution for characterisation. We compared the ability of iRBCs from the sbp2t11up line and its five derivative clonal lines to adhere to bovine brain endothelial cells, using an in vitro cytoadhesion assay. The same lines were selected for in vitro cytoadhesion and the levels of sbp2t11 transcripts in each selected line were quantified. Our results demonstrate that up-regulation of sbp2t11 is accompanied by a statistically significant reduction in cytoadhesion. Confirmed up-regulation of sbp2t11 in B. bovis concomitant with the reduction of iRBC in vitro cytoadhesion to bovine brain endothelial cell is consistent with our previous finding that up-regulation of sbp2t11 is an attenuation marker in B. bovis and suggests the involvement of sbp2t11 transcription in B. bovis virulence.
Bibliographical noteFunding Information:
We are extremely grateful for the technical assistance from Jessica Ujcizo, Debra Alperin, Hanen Baggar, Edith Orozco, Paul Lacy, Monica Pedroni and Linda Hamburg. The design of the study, data collection and analysis, interpretation of data, and writing were funded by Washington State University (USA), College of Veterinary Medicine , intramural grant (AOTL), the United States Department of Agriculture-Agriculture Research Service Current Research Information System Project No. 2090-32000-039-00D, and the International Development Research Centre (IDRC) (Canada) project 108525-001. Gallego-Lopez was supported primarily by a Francisco Jose de Caldas Scholarship from Colciencias-Colombia.
- Babesia bovis
- Spherical body protein
- Stable transfection