Figure 1.

Growth of the influenza delNS1 virus is complemented by transient transfection of an influenza A NS1 protein or an HSV ICP34.5 expression plasmid. MDCK cells were transfected with 4 μg of empty expression plasmid (pCAGGS), pCAGGS-PR8 NS1 SAM (23), or pCAGGS-γ₁34.5. Twenty-four hours later, the cells were infected with influenza delNS1 virus (moi = 0.001). Forty-eight hours posttransfection, viral titers were determined by plaque assay. The results are the average of two independent experiments.