Comparative studies on the purity and specificity of yolk immunoglobulin Y isolated from eggs laid by hens immunized with Toxoplasma gondii antigen.

Eggs from immunized hens were used as a source of yolk antibodies directed against soluble proteins of Toxoplasma gondii. The yolk immunoglobulins (IgY) were extracted and purified by the use of three different methods. The antibody yield and the purity of each batch were determined by protein measurements, gel filtration and isoelectric focusing. A sequence of two precipitation steps, i.e. a precipitation by polyethylene glycol followed by an alcohol treatment, was shown to be the most effective purification method. The specificity of the yolk antibodies was evaluated by means of an indirect hemagglutination assay, an immunodiffusion test and an immunoelectrophoresis. It was compared with the specificity of IgG antibodies obtained from sera hyperimmunized rabbits. The precipitation patterns of IgY and IgG antibodies were non-identical. This results indicates differences between the specificities of egg yolk IgY antibodies and rabbit IgG serum antibodies, although both animal species had been immunized with identical antigen preparations.