Compared to the uninfected condition, mice infected with H9N2 viruses (Wild type or PB2 mutants) exhibited an increase in the numbers of macrophages (CD11b+, CD11c-, Ly6G/c-, CD3-), neutrophils (CD11b+, CD11c-, Ly6G/c+, CD3-), T cells (CD11b-, CD11c-, Ly6G/c-, CD3+) and NK cells (Dx5+, CD3-) since the first day of infection while the dendritic cells (CD11b-, CD11c+, Ly6G/c-, CD3-) increased at day 8. The gene discussed is ITGAX; the disease is infection.