The expression of polyprotein in Bm-N cells was analyzed by IFAT and sandwich-ELISA. IFAT pictures demonstrated that Bm-N cells infected with Bm-P12A3C produced specific fluorescence, while only very weak background fluorescence appeared in the control cells (Fig. 1 ). This indicated that polyprotein was indeed expressed in Bm-N cell. The sandwich-ELISA results indicated that the FMDV antigen in Bm-P12A3C infected cells was expressed at levels about equivalent to the positive control, but was not detected in BmBacPAK-6 infected cell lysate.