Research paperRole of NETs in the difference in host susceptibility to Toxoplasma gondii between sheep and cattle

•It is the first report on production of NETs by sheep and cattle PMNs against to T. gondii tachyzoites in vitro.•Quantity of extracellular DNA from PMNs increased with tachyzoite concentrations and incubation time in sheep and cattle.•Greater concentration of MPO was observed in the cattle PMN-tachyzoites co-culture by fluorescence microscope.•MPO activity was detected higher in the cattle PMN-tachyzoites co-culture than sheep.•In sheep, NETs were responsible for mechanical immobilisation of tachyzoites, but they had lethal effects on tachyzoites in cattle.

The main aim of this study was to compare extracellular traps (NETs) formation by polymorphonuclear neutrophils (PMNs) of cattle and sheep when exposed to T. gondii tachyzoites in vitro. The effects of parasite concentrations and different incubation periods on NETs development in cattle and sheep PMNs were studied. The effect of NET structures on host cell invasion by tachyzoites was also studied. This is the first report of NETs development by sheep and cattle PMNs against T. gondii in vitro. T. gondii-induced extracellular DNA production from PMNs was dependent on tachyzoite concentrations and incubation time in both sheep and cattle. Many nuclear and cytoplasmic changes were observed in sheep and cattle PMNs after exposure to T. gondii tachyzoites. The typical appearance of NETs, with MPO, NE and histone (H3) attached to extracellular DNA, was observed. Tachyzoites were entrapped within this structure. Myeloperoxidase (MPO) activity was higher in the cattle PMN-tachyzoite co-cultures than sheep. NETs structures released from sheep PMNs caused mechanical immobilisation of T. gondii tachyzoites, however, NET structures released from cattle PMNs may be lethal to tachyzoites. Bovine MPO may have a lethal effect on T. gondii tachyzoites in vitro during a 3 h incubation. Besides other mechanisms that effect on host susceptibility to T. gondii in sheep and cattle, extracellular traps formation as a part of immunological reactions may be play a role in host susceptibility to T. gondii.