To determine the cytokine responses that occur after SD/09 virus infection, we measured the levels of five cytokines and chemokines in lungs of infected mice on days 2, 4, 6, 8 and 10 p.i. As shown in Figure 5 , all five were significantly different between virus-infected and control mice. Interleukin (IL)-6 and IL-10 in the virus-infected mice reached peak levels as early as day 2 p.i. and were significantly higher than those of the control group (p,0.001). Interferon (IFN)-c, monocyte chemotactic protein (MCP)-1, and tumor necrosis factor (TNF) dramatically increased in mouse lungs on days 6-8 p.i. (p,0.001), consistent with the appearance of pulmonary lesions. These results showed that infection with SD/09 viruses resulted in elevated amounts of proinflammatory chemokines and cytokines in the lungs of mice.