Fig 2.

Replication of PB1-F2 recombinant viruses in porcine respiratory explants. Explants from nasal turbinates (A), trachea (B), and proximal (C) and distal (D) lung were infected with 10⁶ TCID₅₀ of either Ca/04 WT or KI. The bathing medium was collected at the indicated time points and titrated by the TCID₅₀ method in MDCK cells. Values shown are the mean and range of virus titers (log₁₀ TCID₅₀/ml) obtained from triplicate explant preparations. A two-tailed Student t test was used to determine significant differences between two treatment means for each data point. Dashed brackets indicate statistically significant differences (P < 0.05).