S100A9 and infection: In this study, several components of the downstream IL-17 signalling were downregulated by tick infestation including IL17RC, IL17RA, TRAF6, IKBKE, MAPK1, IKBKB, IKBKE, NKFBIA, FOS, the chemokine gene GRO1, cytokine gene PTGS2, and antimicrobial genes DEFB10, S100A7, S100A8, S100A9. Similar findings in mice studies have been reported for the downregulation of IL-17 receptors (IL-17R) during pathogen infection [50], and the host Th17 immunity during infestation with Ixodes scapularis ticks [51].