CXCL1 and infection: PRRSV pre-infection of cells did not influence, in general, the activation of such genes by S. suis. Conversely, some genes implicated in the inflammatory response were downregulated following stimulation by S. suis or both pathogens, such as those coding for the chemokine receptors CCR3 (receptor for CCL5, -11, -13, and -28) and CXCR2 (receptor for CXCL1, -2, -3, -5, -7, and -8) (S4 Table).