25. In vitro evaluation of the antibacterial proprieties of chicken egg yolk immunoglobulins: promising results supporting their use in vivo

This chapter gives an overview of the inhibition effect of chicken immunoglobulin Y (IgY) on adhesion and growth of pathogenic bacteria in vitro. Bacterial adhesion suppression data are only presented for the gastro-intestinal bacteria, which are mostly Gram-negative bacteria. Data related to the bacterial growth inhibition are presented for both Gram-negative and Grampositive bacteria. It has been demonstrated that IgY directed against a given bacterium (i.e. whole cell) or an antigenic target belonging to the bacterial surface can partly inhibit bacterial adhesion, and in some reports, totally suppress the bacterial growth. It is important to note that both of these anti-bacterial proprieties of IgY are affected by numerous factors, especially the antigenic target, the purity and the concentration of the IgY preparation. The more the IgY were specific for a key antigen and presented a high level of purity, the more they were effective in inhibiting the bacterial adhesion and growth. Moreover both of these anti-bacterial effects were dose-dependent and seem to be related to the specific binding of IgY to particular components located on the bacterial surface, which are implicated in adhesion process or are crucial factors for the bacterial growth. Further research work is necessary to understand fully the antibacterial mechanisms of IgY.