In summary, at the late phase of infection (i.e. 18 and 24 hours post-infection), TNF-α, IL-6, IL-8, CCL-5/RANTES and CXCL-10/IP-10 mRNA remained at high levels for H5N1/2004 and H9N2/1997; which were in contrast to those observed for H1N1/2002 (Figure 2, Table 2). Here, CXCL10 is linked to infection.