Chickens were immunized with purified recombinant green fluorescent protein (GFP) emulsified in Freund’s adjuvant. After multiple injections, eggs were collected from the hens, and IgY fractions were prepared from the yolks. Purified antibody preparations were then mixed with glycerol 1:1 (v/v) (to prevent freezing at -20°C), augmented with thimerosal, and then filter-sterilized.