CXCL8 and infection: As shown in Figs 5B–5E, significant increases of IL-6, IL-8, TNFα, and IL-1α were observed in the vWT and S. suis co-infection group, compared to the vWT single-infection group, indicating that co-infection of PRRSV-2 and S. suis enhanced the proinflammatory cytokine expressions.