Gutiérrez-Expósito, D.Silva, L. M. R.Wagner, H.Gärtner, U.Hermosilla, C.Taubert, A.Conejeros 1st2026-06-082026-06-082026-07Gutiérrez-Expósito, D., Silva, L. M. R., Wagner, H., Gärtner, U., Hermosilla, C., Taubert, A., & Conejeros (2026). Comparative ex vivo responses of ovine and bovine polymorphonuclear neutrophils induced by Neospora caninum tachyzoites. Veterinary parasitology, 345, 110797. https://doi.org/10.1016/j.vetpar.2026.1107971873-2550http://hdl.handle.net/10400.26/63539Neospora caninum infection causes reproductive failure in ruminants with a traditionally higher incidence of bovine neosporosis compared to the ovine system. Differences in innate immune response could explain this observation. We here focused our study on the comparison of the N. caninum-induced response on bovine and ovine polymorphonuclear neutrophils (PMN) that might play a key role in the pathogenesis of neosporosis in both small and large ruminants. We here examined and compared in parallel PMN responses of healthy adult sheep (n = 6) and cows (n = 6) after exposure to N. caninum tachyzoites (ratio 1:4). PMN activation was evaluated by induction of NETosis, determined by immunofluorescence and scanning electron microscopy (SEM), extracellular reactive oxygen species (ROS) production via Amplex Red assays, and oxygen consumption rates (OCR) and proton efflux rates (PER) quantified by Seahorse XF technology. N. caninum tachyzoite-driven percentage of NETotic PMN was higher in the bovine system (24.4%) when compared to sheep (11.3%). For both, SEM analyses confirmed PMN activation and the formation of NET structures upon N. caninum tachyzoite exposure. The increase in tachyzoite-mediated ROS production proved higher in cattle than in sheep and these data were in line with significantly higher PER on bovine PMN indicating a differential glycolytic activity upon N. caninum exposure. Overall, this study documents early (minutes) and mid-late (hours) ovine and bovine PMN reactions after being exposed to N. caninum tachyzoites. The fundamental information here given contributes to the understanding of neosporosis in cows and sheep that should be complemented with in vivo studies.engNETs formationROSInnate immune responseNeospora caninumCattleSheepcontribution to journal10.1016/j.vetpar.2026.110797