International reference preparation of anti-Mycoplasma gallisepticum serum

The WHO Expert Committee on Biological Standardization requested the Central Veterinary Laboratory, Weybridge, England, to arrange a collaborative assay of material they had prepared to determine its suitability to serve as an international reference preparation of anti-Mycoplasma gallisepticum serum. Fourteen laboratories in eight countries performed comparative assays of the proposed reference preparation together with 3 immune sera from fowls. On the basis of the results obtained, the Committee established the preparation as the International Reference Preparation of Anti-Mycoplasma gallisepticum Serum and defined the International Unit as the activity contained in 0.0556 mg of the International Reference Preparation.