FIG 11.

Effect of PA-X 195K on the suppression of nonviral protein expression of H9N2 PA-X in avian cells and replication of H9N2 virus in chickens. (A) GFP expression in DF-1 cells cotransfected with expression vectors encoding GFP, together with expression vectors encoding either the PA-X (195K) or PA-X (195R) gene of H9N2 virus at 24 h posttransfection. 293T cells, untransfected or cotransfected with GFP expression plasmids and empty pCAGGS vector, served as controls. (B) Luciferase expression from pCAGGS-Luc in DF-1 cells cotransfected with either empty pCAGGS plasmid (Vector) or pCAGGS containing the indicated genes for 24 h. The results are shown as means and standard deviations (n = 3 biological replicates; n = 3 technical replicates). (C) Three 6-week-old SPF chickens per group were inoculated intranasally with 10⁶ EID₅₀ of the indicated viruses. The next day, the inoculated animals were individually paired by cohousing them with direct-contact chickens. To monitor viral shedding, tracheal swabs were collected from all the animals every other day for 8 days. The dashed line indicates the lower limit of detection.