IFNA1 and infection: After generation of virus stocks, growth kinetics of both viruses were assessed by plaque assay (Fig. 1B–D) and quantitative reverse transcription PCR (RT-qPCR) (Fig. 1E, F) in Vero (IFN-deficient) and A549 (IFN-competent) cells at multiplicities of infection (MOIs) of 0.01 and 0.1 (Fig. 1B–F).