Fig. 4.
Replication and pathology induced by PB1-F2 recombinant viruses in swine. Pigs (n = 10 per group) were infected with 105 TCID50 virus and nasal swabs were collected from days 1 to 3 p.i. to measure virus shedding. Lungs were collected at 1 and 3 days p.i. (n = 5 day−1) for virus titration and pathological analysis. (a, b) Virus shedding in nasal secretions. (c, d) Pulmonary replication of PB1-F2 isogenic viruses in pigs (measured as virus titre in BALF). (e) Percentage of macroscopic lung lesions. (f) Lung histopathology scores. Data are presented as means±sd of five independent experiments. Dashed brackets indicate a statistically significant difference (P<0.05).