Propagation of H9N2 Influenza Viruses

Human bronchial epithelial (Calu-3) cells and chicken fibroblast (DF-1) cells were obtained from the American Type Culture Collection, and MDCK cells and 293T cells were obtained from the RIKEN BioResource Center Cell Bank. The cells were maintained in Dulbecco’s Modified Eagle’s Medium with 10% FCS. Influenza virus A/chicken/Egypt/CL42/2013 (EG/2013) (H9N2) is a representative strain of the G1-A/B reassortant that has been prevalent in Egypt and has been described previously [20 (link)]. All recombinant H9N2 viruses were propagated once in 10-day-old embryonated eggs. The sequences of the EG/2013 gene segments have been deposited in the GenBank database (accession nos. LC379963-LC379970).