The effect of early cyclophosphamide treatment on the subsequent immunity of chickens to coccidial infections

Chicks were treated with cyclophosphamide during the first 3 days of life in order to effect chemical bursectomy. They subsequently showed a reduced capacity for the production of serum agglutinins toBrucella abortusand immunolysins to sporozoites ofEimeria tenella. They also developed a reduced immunity toE. tenellaorE. maximacompared with that produced in normal birds. The evidence provided by these experiments for the role of circulating antibodies in immunity to coccidiosis is discussed.