Growth inhibition of Staphylococcus aureus by chicken egg yolk antibodies

The aim was to evaluate the ability of egg yolk antibody (IgY) in blocking Staphylococcus aureus growth in vitro.

Specific IgY was produced by immunizing hens with formalin-killed S. aureus (ATCC 33593). Specific IgY against S. aureus was obtained from the yolks of their eggs with a carrageenan solution. IgY was identified by SDS-PAGE and Western blot and its activity against S. aureus was tested by ELISA. A growth inhibition assay and protein concentration determination were also conducted.

ELISA indicated that the IgY was specific to the antigen; this activity was confirmed by Western blotting. The growth of S. aureus was inhibited by the specific IgY at concentrations of 1-5 microg/ml The bacteriostatic function of IgY appeared to result possibly from the interaction of IgY with surface components of S. aureus. In vitro experiments showed that the immunoglobulin from egg yolk interfered with the culture growth of the S. aureus.

These findings indicate that eggs from hens immunized with appropriate antigens are a potentially useful source of passive immunity.