FIG 7.

Replication kinetics of EG13 and D1 viruses carrying PA mutations in human and avian cells. (A to C) Avian DF-1 cells (A) and human Calu-3 cells (B and C) were infected with the EG13-wt virus or an EG-13 virus carrying the indicated PA mutant at MOIs of 0.003 and 0.03, respectively, and incubated at 37°C (A and B) and 33°C (C). (D to F) Avian DF-1 cells (D) and human Calu-3 cells (E and F) were infected with the reassorted D1/PA viruses carrying PA-wt or PA with the indicated mutation, PB2, PB1, and NP from EG13, and the other genes from D1, at MOIs of 0.003 and 0.03, respectively, and incubated at 37°C (D and E) or 33°C (F). At the indicated times postinfection, the progeny virus titers were measured by FFU assays. Each data point is the mean ± SD from three independent experiments.