Abstract: Objective · To compare the response and consequence of momacrophages infectedLeptospira interrogans 56606v and 56606a, and explore the mechanisms of pathogenic Leptospira to cadisease. Methods · Peritoneal macrophages of C57BL/6 mice were infectedpathogenic Leptospira 56606v and non-pathogenic Leptospira 56606a respectively. Immunofluorescence staining was performed to observe phagocytosis and clearance of Leptospira after infection, and realtime-PCR was used to determine cytokine production of macrophages. Results · After 72-hour infection, strain 56606v exhibited a lower phagocytic rate but survived after incubation with peritoneal macrophages compared with strain 56606a, which showed a higher phagocytic rate but was cleared at that time point. Additionally, cytokine production of macrophages incubated with 56606v was lower than that with 56606a. Conclusion · Leptospira interrogans strain 56606v can survive in macrophages, which may contribute to evasion phagocytic clearance and lead to disease, while strain 56606a can be cleared, which implicates a lower pathogenicity.

Key words: Leptospira interrogans, macrophage, phagocytosis, inflammatory response, immune surveillance