Specific IgG activity of bovine immune milk against diarrhea bacteria and its protective effects on pathogen-infected intestinal damages

Bovine milk antibodies of lactating cows immunized with a multivalent vaccine consisting of whole cells of 17 strains of pathogenic diarrhea bacteria were generated. Using an in vitro mimicked intestine pH environment, we demonstrate that strong activity of their specific IgG may be recovered through the gastrointestinal tract to prevent pathogen-infected intestinal damages, thereby potently inhibiting pathogen-induced diarrhea. This is supported by histological and ultrastructural evidence that specific IgG may effectively abolish pathogen-induced cellular dysfunction of small intestinal mucosa, including tight junctions, brush border, enterocytes, goblet cells, etc. Normal IgG from non-immunized milk is incapable of eliciting the same consequences as specific IgG. Furthermore, we also noticed that specific IgG exerts an effective protection by enhancing splenic natural killer (NK) cell activity in pathogen-infected mice. Our findings indicate that the specific IgG from milk antibodies of immunized lactating bovine may be exploited in therapies for prevention of multibacteria-induced diarrhea.