Specific IgG activity against diarrheagenic bacteria in bovine immune milk and effect of pH on its antigen-binding activity upon heating.

Bovine colostrum and milk antibodies of calving and lactating cows immunized with a multivalent vaccine consisting of whole cells of three different species of pathogenic bacteria including four strains of enterotoxigenic Escherischia coli, five strains of enteropathogenic Esch. coli, three strains of enteroinvasive Esch. coli, two strains of Samonella typhi, and one strain each of Shigellia dysenteriae, Sh. sonnei and Sh. flexneri were generated, respectively. A significantly elevated activity and titre of specific IgG from bovine immune colostrum were seen for only 5 days after calving of immunized cows, however, the levels of specific IgG could be obtained continuously from the milk of immunized lactating cows until the 11th week of the entire experiment period. Subsequently, we observed that the high specific IgG activity in immune milk was relatively stable under pH 5.0-7.0 at 37 degrees C. Of importance, we identified that the specific IgG preserved its biological function for high antigen-binding activity at pH 5.5-6.5 for 30 min of heat treatment at 70 degrees C and for 350 s at 72 degrees C. Our findings suggest that the specific IgG from milk antibodies of immunized lactating cows may be used as an abundant source of hyper-immune products for prevention of multibacteria-induced diarrhea, however, the effect of pH on its antigen-binding activity upon heating should be carefully considered and designed.

Bovine immune colostrum against 17 strains of diarrhea bacteria and in vitro and in vivo effects of its specific IgG.

Bovine colostral antibodies of cows immunized with a multivalent vaccine consisting of whole cells of 17 strains of pathogenic diarrhea bacteria were generated, and the specific IgG with high activities and titres directed against these pathogens was purified using an ammonium sulfate precipitation and verified by SDS-PAGE. We demonstrate that specific IgG has a strong activity of inhibiting in vitro growth and colonization in pathogens by agglutinating with bacteria and destroying cell walls. Normal IgG purified from non-immunized bovine colostrum is incapable of eliciting the same consequences as specific IgG. Specific IgG prevents enteroinvasive Escherichia coli/Salmonella typhi-induced diarrhea and may exert an effective protection by enhancing splenic NK cell activity, elevating IL-2 level and inhibiting excessive release of TNF-alpha in mice. Thus, the specific IgG from colostral antibodies of immunized bovine can provide effective protection or therapy for multibacteria-induced diarrhea.