Quantitative Immunological Comparison of Bird Lysozymes*

Rabbit antisera were prepared against crystalline chicken lysozyme and characterized by immunodiffusion, immunoelectrophoresis, inhibition of enzyme activity, and quantitative micro-complement fixation. Lysozyme was purified by Sephadex G-75 chromatography from the egg whites of 17 species of birds in the order Galliformes and was tested for reactivity with anti-chicken lysozyme. The chicken and its closest relative, the jungle fowl, have lysozymes that appear to be indistinguishable from each other. The lysozymes of all the other species tested (e.g. partridges, quails, and pheasants) could be distinguished from the chicken enzyme by quantitative micro-complement tiation. Immunodiffusion failed to detect most of these differences in antigenic structure. A particularly close relationship was observed between the lysozymes of the chicken, partridges, and American quails. This suggests that these lysozymes may show very small sequence differences. This finding may also have taxonomic significance.