Comparison of infection with different strains of pdmH1N1 virus in A549 cells. The figure shows the comparative analysis of cellular immune mediators after NC2, NC8 and NC11 infection. Cells were infected with respective viral strains while mock infection with HBSS was given to blank. At different time points, mRNA expression of different cytokine/chemokine genes was measured by real time RT-PCR. Results are presented as log 2 of mean arbitrary units ± SEM. Data are compared by Mann Whitney U test. *** _P < 0.0001, **_ P <0.001, * _ P <0.01.