Bm-N cell line was co-transfected with baculoviral transfer plasmid pVL-P12A3C and linearized BmBacPAK-6 DNA. The supernatant was collected 4 days post transfection as the viral stock for screening of recombinant virus. Twenty four isolated viral plaques from the plaque assays were cultivated in a 24-well plate and were inoculated into silkworms. The plaque of recombinant virus expressed at maximal activity was selected to purify. The pure recombinant virus from the last round was used as stock virus and confirmed to contain the full expression cassette. The recombinant virus Bm-P12A3C was used to express FMDV protein in cells or silkworm.