Figure 1

Western blot analysis, growth kinetics, and plaque phenotyping of the recombinant viruses. Immunoblot of the NS1 protein in extracts from MDCK cells infected with PR/8, PR/8 × KYG^NS, and PR/8 × MI^NS viruses at an MOI of 1 for 12 h (A). The protein was detected using a mouse anti-NS1 primary antibody, and the molecular weight in kDa is shown on the left of the membrane. MDCK (B) and A549 (C) cells were infected with the PR/8, PR/8 × KYG^NS, or PR/8 × MI^NS virus at an MOI of 0.01, and the virus was titrated in the supernatant that was collected at the indicated time points. The detection limit was 1 log₁₀ TCID₅₀/mL (dotted line). Data are shown as the mean ± standard deviation from three independent experiments. Plaque assay performed with PR/8, PR/8 × KYG^NS, and PR/8 × MI^NS viruses (D). The tissue culture plates infected with the viruses were fixed and stained with crystal violet dye.