TNF and infection: Macrophages and supernatants were collected after different times (0h, 4h, 12h, 24h and 48h) of B. abortus-infection, and mRNA expression of macrophage M1 (Tnfα, Nos2 and Il1β) and M2 (Tgfβ, Arg1, Il10) polarization marker genes were detected by RT-qPCR.