Fig 3.

Differential PB1-F2 expression is dependent on the PB1 gene. MDCK cells were infected with rPR8, rMx/PR8, rPR8/MOM, or rMx/MOM at an MOI of 2, and at 12 h p.i., the cells were fixed and immunostained with antibodies against NP and PB1-F2, followed by Alexa Fluor-conjugated secondary antibodies. The percentage of NP-expressing cells also expressing detectable amounts of PB1-F2 was determined and plotted on a graph. Statistically significant groups (P < 0.05) compared to PR8-infected samples are denoted with asterisks. The error bars indicate standard deviations.