FIGURE 6.
Production of PB1-F2 during infection. Recombinant A/Puerto Rico/8/1934 carrying PB1-F2 (68T, 69Q, 70E, 71S) was made using an eight-plasmids reverse genetics system. Plasmid pHW192 or pHW192-(PB1-F2 TQES) was transfected with seven other plasmids into HEK293 cells to generate PR8 wild-type (wt) virus or PR8 (PB1-F2-TQES) mutant virus, respectively. Transfected cells and supernatant were collected 48 h later. 2.5 × 105 A549 cells were inoculated with 0.25 ml, 0.5 ml, and 1 ml of supernatants and harvested 24 h post-infection. Both transfected HEK293 and infected A549 cells were subjected to Western analysis for viral protein productions using antibodies indicated.