The expression of FMDV polyprotein in Bm-N cells infected with Bm-P12A3C was analyzed by immunofluorescence test (IFAT) and sandwich-ELISA. The Bm-P12A3C was multiplied in Bm-N cells. Bm-N cells (2.0610 5 ) were cultured on cover slips and inoculated at a MOI of 10 pfu with Bm-P12A3C. After 48 hours post infection (hpi), IFAT was conducted to analyze the expression of FMDV proteins. Cells were then rinsed with PBS for 1 or 2 times and fixed in 100% cold acetone (220uC for 30 min). Samples were incubated with rabbit serum against FMDV (37uC for 30 min) in humid box, washed with PBS for five times, and then stained with fluorescein-conjugated goat anti-rabbit serum at 37uC for 30 min. The cover slips were coated with glycerin and observed on an Olympus fluorescence microscope. Bm-N cells infected with BmBacPAK-6 were used as control.