In sera, only the peak concentrations of Cxcl1 (8 h), Ccl2 (8 h), Ccl3 (8 h), IL-1β (4 h), and IL-6 (4–8 h after infection) were significantly elevated in ExoY-infected mice as compared to ExoYK81M-infected mice (Figure 4). This evidence concerns the gene CCL2 and infection.