IL6 and infection: In cotton rats, influenza virus infection rapidly induces many inflammatory cytokines starting soon after infection (within 1 to 3 days p.i.), including beta interferon (IFN-β), interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-α), coinciding with virus replication, and these cytokine levels wane by days 6 to 8 p.i.