Chicken Egg Yolk Antibody (IgY) Powder Against Escherichia coli O78:K80

摘要

The growth inhibitory effect of egg yolk antibody (IgY) powder for food application was investigated on Escherichia coli O78:K80, as a model and the major cause of associated septicemic disease in broiler chickens. Laying hen?s hyperimmunized with E. coli O78:K80 bacteria for a 12 weeks period and IgY was isolated by the water-dilution method. E. coli O78:K80 was incubated with IgY (50, 100 and 150 mg mL-1 specific and non-specific IgY powder) for 6 h during, which samples were taken at 2 h intervals. After the first immunization, the antibody specific activity in serum and egg yolk increased and became plateau on day 7 and 14, respectively. The protein concentration of serum and IgY powder did not change during the immunization period, but the ratio of gamma globulins to total serum protein and IgY purity (total IgY in protein) of IgY powder increased (p<0.05) and remained high throughout the experimental period. Specific IgY powder at the concentration of 150 mg mL-1 decreased bacterial proliferation by 1.18 log CFU mL-1 compared with the control group at 6 h of incubation period (p<0.01). Results of this study suggest that E. coli O78:K80 could have long term antigenic properties to induce an immune response in laying hens. The large-scale and long-term production of IgY, with high purity and high specific activity, can be attained by water dilution method. The inhibitory effect of specific IgY powder may encourage IgY powder to be applied as a feed additive to protect against E. coli O78:K80.