Characterization of egg yolk immunoglobulin (IgY) against enterotoxigenic Escherichia coli and evaluation of its effects on bovine intestinal cells

Abstract

Enterotoxigenic Escherichia coli (ETEC) infection is common in calves. Egg yolk antibodies (IgY) have been used to treat gastrointestinal infectious diseases. This study aimed to characterize IgY against bovine ETEC and to evaluate its effects on bovine intestinal cell culture challenged with a bovine ETEC strain. IgY was isolated from the egg yolks of hens immunized with ETEC. The characteristics of IgY were determined by Bradford, ELISA, gel electrophoresis and immunoblotting. Significant differences in anti-ETEC activity between anti-ETEC IgY and non-specific IgY were found in lyophilized fractions. In the bacterial growth assay, anti-ETEC IgY (40 mg/mL) showed growth inhibition of ETEC after 2 h of incubation (p<0.05). The difference in bacterial growth between anti-ETEC IgY and non-specific IgY groups was 0.51 log CFU/ml after an 8 h incubation (p<0.05). The bacterial adhesion assay indicated that anti-ETEC IgY (40 mg/ml) significantly decreased the adhesion of ETEC to bovine intestinal epithelial cells within 4 h (about 1.36 log units compared with the control group; p<0.05). This study demonstrates that anti-ETEC IgY inhibits the growth and adherence of ETEC to bovine intestinal cells and is a potential alternative to traditional treatments of E. coli infections. Key words: Immunoglobulin Y (IgY), neonatal calf diarrhea, enterotoxigenic Escherichia coli, bacterial adherence, bacterial growth