Production of Egg Yolk Immunoglobulin (IgY) Against Recombinant LTB of Enterotoxigenic Escherichia coli (ETEC) and Evaluation of Its Protective Effect in Animal Model

Enterotoxigenic Escherichia coli is one of the most common bacterial causes of diarrhea worldwide. One of the most important ETEC colonization factors is B subunit of the Heat Labile Enterotoxin, which forms the connecting part of the toxin. In the present study, egg yolk immunoglobulin (IgY) was produced and its effectiveness against recombinant LTB protein was tested on the animal model.

Hens were injected intramuscularly with 100 μg of recombinant LTB protein. The antibody titer was estimated and the eggs were collected. The water soluble part of the yolk was separated and the antibody titer was subsequently estimated by ELISA.Effecacy of different concentrations of IgY on nutralising the effect of LT toxin on Y1 cells was also studied. In order to investigate the effect of IgY-treated bacteria on intestinal epithelial cells, the standard Ileal loop  technique was used.

Protein expression led to the production of recombinant LTB showing molecular weight of 11 kDa on SDS PAGE. Immunization of hens induced serum antibody rise. The purified antibody was 144 mg per 12 ml of egg yolk. Purified IgY exhibited significant effect against recombinant LTB proteinAt the concentration of 125 μg per ml, the IgY could prevent the effects of Heat Labile Enterotoxin on Y1 cells. In the Ileal loop test, 1.5 mg / ml IgY neutralized the toxin effect of LTB   on the intestine. The accumulation of fluid in the test loops decreased by 74.8% compared to the untreated control loops.

The results showed that specific egg yolk immunoglobulin was effective against recombinant LTB protein and can be used as a preventive antibody to inhibit the Heat Labile Enterotoxin function of ETEC bacteria.