Investigation on neutralizing efficacy against verotoxin and resistance to protease of bovine immune colostral antibody in mice and beagle dogs

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The bovine colostral antibody against verotoxin2 (VT2) was not inactivated after 2 hours after oral administration. However, the activity of serum antibody reduced 15% of prior administration in the small intestine of beagle dogs. Furthermore, the antibody activity of S-IgA did not change; however, the activity of IgG and IgM antibodies decreased after 2 hours of oral administration. With oral administration of bovine colostral whey without antibody in beagle dogs inoculated Escherichia coli (E.coli) O157:H7 producing VT2, the amount of VT2 in feces decreased gradually after administration and increased again at 5 days after inoculation, while bovine colostral antibody significantly reduced the amount of VT2 in feces the day after oral administration of bovine colostral antibody. Mice were administered orally each immunoglobulin class antibody isolated from bovine colostral whey obtained from cows immunized with VT2, serum antibody or bovine colostral antibody at 1h after administration of VT2. All mice died after administration of sterilized saline as control. The survival rate was 93.3% after administration of S-IgA or IgM class antibody, or bovine colostral antibody. The survival rates for IgG class antibody and serum antibody were 80% and 60%, respectively. These results suggest that bovine colostral antibody against VT neutralized the activity of in small intestine by resistance to protease.