Silkworm haemolymph was lysed ultrasonically and cell debris was removed by centrifugation. The diluted supernatant was used to produce vaccine. Liquid-phase blocking ELISA(LPBE)(http:// www.oie.int/eng/normes/MMANUAL/A_00024.htm) was performed to determine the antibody titer for screening of candidate cattle according to the standard method of World Organization for Animal Health, Office International desEpizooties (OIE) before vaccination. Candidates with a potency lower than 8 were housed in disease-secure isolation facilities in Lanzhou Veterinary Research Institute. Detection kit was prepared by Lanzhou Veterinary Research Institute. Seven cattle (6-8 months old) were immunized by intramuscular inoculation at the site in the neck.