CCL2 and infection: Unlike H5N1, H1N1 induced significantly lower levels of IL-6, MCP-1 and TNF-α at 24 h post-infection; and MCP-1, TNF-α, IL-10, IFNL1 and IFN-β at 48 h post-infection when compared with H7N9-CK or H7N9-HU.