C2 and infection: In this study, the expression of c1r, c2, c3, c7, c8b, c9, cfh and c1qtnf6 were significantly up-regulated in the control group at 4 hpi post-infection, and the expressions of c1r, c6, c1qbp and c1qtnf6 in the MOS200 or MOS400 groups were higher than that of the control group before or post-infection.