FIG 9.

IFN-α, IFN-β, and IFN-γ mRNA expression levels in mouse lungs at the indicated times were determined by real-time RT-PCR. Mice that received different immunization regimens on day −3 were infected with 10 times the LD₅₀ of mouse-adapted A(H1N1)pdm09. Relative levels of IFN-α, IFN-β, and IFN-γ mRNA expression were determined by real-time RT-PCR with gene-specific primers (A, B). Lung samples from uninfected mice (n = 3) were used as the baseline control to compare the changes in gene expression. n = 9 for the PBS group; n = 8 for other groups. Error bars indicate standard deviations. *, P < 0.05; **, P < 0.01 (compared with the vaccine day −3 group).