Cattle were vaccinated by the vaccine prepared from 1/30 diluted expressed antigens (the quantity of antigen was about 3 folds of the BHK-21 cell vaccine). LPBE-antibody titer was determined at 7, 14, 21 and 28 dpv following the LPBE method. It was found that all five cattle vaccinated with Bm-P12A3C antigen developed a detectable FMDV-antibody response at 7 dpv, and dramatically reached to high level at 14 dpv. By 21and 28 dpv, the antibody level was maintained at the same level or higher, and reached to a titer of 360 in cattle No33 and No50. In contrast, antibody level in the two control cattle (vaccinated with vaccine prepared from BmBacPAK-6) was not boosted (Table 1) .