(A, B) 293T cells were transfected with pHH21-vNS-Luc (left panel) or pHH21-cNS-Luc (right panel), NP, PA, PB1, PB2 expression plasmids, and 50 ng, 100 ng, 200 ng of pCMV-Myc-Hsp70 or 200 ng of pcDNA3.1 as negative control, then subjected to luciferase assay (A) and immunoblotting with indicated antibodies (B). (C) 293T cells were transfected with pHH21-vNS-Luc (left panel) or pHH21-cNS-Luc (right panel), plasmids encoding NP, PA, PB1, PB2, and 200 ng of pCMV-Myc-Hsp70, pCMV-Myc-Hsp70ΔEEVD, pCMV-Myc-Hsp70 ATPase domain, pCMV-Myc-Hsp70 PBD or 200 ng of pcDNA3.1 as negative control. The luciferase assays were performed accordingly. The data represent the means of two independent experiments, each performed in triplicate. Error bars represent standard deviation (n = 3). (D) The protein levels were analysed by immunoblotting with indicated antibodies.