FIG 4.

Replication kinetics of influenza viruses in polarized human airway epithelial cells. Calu-3 cells grown on transwells were infected apically in triplicate at an MOI of 0.01 with Pin/WA/40964 (H5N2), Gyr/WA/41088-6 (H5N8), Bris/59 (H1N1), or Th/16 (H5N1). The cells were incubated at 37°C (A) or 33°C (B), and culture supernatants were collected at 2, 16, 24, 48, and 72 h p.i. for virus titer determination by standard plaque assay. Asterisks indicate the statistical significance between Th/16 and other tested H5Nx viruses (*, P < 0.05; **, P < 0.01; ***, P < 0.001).