CCL3 and infection: After infection with each virus (104 PFU), lungs from three mice per group were collected at day 1, 3, 5 and 7 p.i. and the levels of cytokines (IL-6, IL-1β, TNF-α, IFN-γ) and chemokines (MIP-2, MIP-1α, MCP-1) in lungs were analyzed by ELISA.