FIG 2.

Pandemic H1N1 induces significantly less IL-1β than SIVs. (A) PAMs were infected with an SIV strain, Sk02, or a human pandemic strain, Hf09, at an MOI of 1. At 24 hpi, cell-free supernatants were harvested for IL-1β ELISA, and the cells were lysed for Western blotting to measure the expression of pro-IL-1β and viral NS1 protein. ns, not significant, ***, P < 0.001. (B) PAMs were infected with Sk02 or Hf09 at an MOI of 1, and the supernatants were harvested at 8, 16, and 24 hpi. IL-1β was measured by ELISA, and viral titers were determined by plaque assay on MDCK cells. Two-way ANOVA with Tukey's multiple-comparison test was used to compare IL-1β levels (***, P < 0.001), and a Mann-Whitney test was used to compare virus titers (ns, not significant). Results are representative of three independent experiments.