Evaluation of host immune mediators. Transcriptional data for major host immune response genes (b-f) and viral mRNA levels (a) are shown at 1d.p.i. in C57/BL6 mice infected with 105 EID50 of various strains of pandemic H1N1 influenza virus (NC2, NC8 and NC11) and mock infection with HBSS was given to blank animals. Results are presented as mean ± SEM of mRNA levels normalized with mouse β-actin gene. Statistical differences were calculated by Mann Whitney U test. ** - P < 0.001, * - P < 0.01.