TLR9 and giardiasis: Corroborating the findings of our present study, the G. duodenalis–induced secretion of IL-6, TNF-α, and IL-12 p40 was decreased in siTLR9-treated mouse macrophages and WT mouse macrophages pretreated with p38 and ERK inhibitors, implying that the TLR9–p38/ERK signaling pathways activated by G. duodenalis may contribute to host defenses against Giardia infection.