Application of freeze-dried, one-day-old chick erythrocytes to viral hemagglutination and hemagglutination-inhibition tests.

Erythrocytes collected from 1-day-old chicks were stabilized by fixation with formaldehyde and by freeze-drying after treatment with carbon monoxide. Suspensions of freeze-dried erythrocytes in distilled water or physiological saline had a homogeneous bright reddish-purple color. Freeze-dried erythrocytes were compared with fresh erythrocytes for hemagglutination and hemagglutination-inhibition tests for various viruses including rubella, Japanese encephalitis, influenza, mumps, Newcastle disease, and Sendai viruses. After storage at 4 degrees C for 1 year or more, freeze-dried erythrocytes maintained their original appearance and sensitivity to hemagglutination antigens.