Authors
P Sharma3; S Egon2; R Flynn1; 1 University of Liverpool; 2 University of Nottingham; 3 University of Nottingham/University of Liverpool Discussion
Neospora caninum is an intracellular protozoan parasite which causes abortion in cattle and neuromuscular disease in dogs. Bovine infection can be initiated in utereo or after birth through ingestion of infectious material. Our previous studies have shown differences in young monocytes compared to adult cells in terms of cytokine responses and expression of CD80. In this study we investigated if there was an age dependent effect on invasion of monocytes and their subsequent interaction with NK cells during N. caninum infection. NCLiv-1 isolate of N. caninum was maintained in a VERO cell line. Naive CD14+ and NK-cells were isolated from peripheral blood mononuclear cells (PBMCs) from young and adult cattle by magnetic cell separation. Monocytes were sequentially infected with N. caninum CFSE labelled tachyzoites before co-culture with NK cells. The number of infected cells was determined post-culture and CD80 expression, as a marker of cellular activation, was determined by flow cytometry. There was an age-related variation in infection of monocytes with cells derived from old animals more likely to harbour greater numbers of parasites. A reduction in parasite numbers post culture with NK cells was noticed in both young and adult cattle with increased CD80 expression also observed. The greater uptake of parasites into monocytes in combination with NK-cell interaction inhibits parasite multiplication and may be one mechanism to explain the age-related differences in innate immune response to intracellular parasitic (N. canium) infection. 
