FGFR1 silencing by RNAi increased influenza A/PR8 and H5N1 virus replication.

<p>(<b>A</b>-<b>D</b>) A549 cells were transiently transfected with specific siRNA targeting FGFR1, FGFR4, or negative control siRNA. Forty-eight hours later, A549 cells were infected with PR8 virus at an MOI of 1. The cell culture supernatants and cell lysates were obtained at 24 hpi. Influenza virus M1 mRNA expression in A549 cells with PR8 (<b>A</b>) or H5N1 (<b>B</b>) infection was detected using real-time PCR. Progeny virus titers of PR8 (<b>C</b>) or H5N1 (<b>D</b>) were determined using MDCK cells with the TCID₅₀ assay. (<b>E</b>) The knockdown efficiencies of FGFR1 and FGFR4 by target siRNA were tested using real-time PCR. (<b>F</b>) Protein expressions of FGFR1 and FGFR4 were detected using specific antibodies by Western blotting assay. All graphs represent the means ± s.e.m. (n = 3). Values of P<0.01 **and P<0.001 *** were considered statistically highly significant.