Figure 6.

Invasion assays of N. caninum tachyzoites after polymorphonuclear neutrophil (PMN) exposure. Neospora caninum tachyzoites were cocultured with bovine PMN for 3 h (=PMN + Nc) allowing for effective neutrophil extracellular trap (NET) formation. In parallel, DNase I was supplemented to the tachyzoite-PMN-suspension 15 min before the end of the incubation period (=PMN + Nc + DNase I) to dissolve potential NET structures. The same number of non-treated tachyzoites in plain medium served as infection controls (=Nc only). Following incubation, the differentially treated tachyzoites were transferred to confluent bovine umbilical vein endothelial cell (BUVEC) monolayers for infection. Twenty-four hours p. i., the BUVEC layers were thoroughly washed and infection rates were estimated. Arithmetic means and SDs of three PMN donors and three BUVEC isolates, minimum, and maximum were calculated. Differences were regarded as significant at a level of ***p ≤ 0.001 and ****p ≤ 0.0001.