International Reference Preparation of Anti-Newcastle-Disease Serum

Abstract The Central Veterinary Laboratory, Weybridge, England, was requested by the WHO Expert Committee on Biological Standardization to obtain suitable material for an international reference preparation of anti-Newcastle-disease serum for standardizing the haemagglutination-inhibition test for Newcastle disease and to arrange a collaborative assay. Ten laboratories in 10 countries assayed a batch of immune chicken serum against 2 test preparations. On the basis of the results obtained, the material has been established as the International Reference Preparation of Anti-Newcastle-Disease Serum and the International Unit of Anti-Newcastle-Disease Serum has been defined as the activity contained in 0.1734 mg of the International Reference Preparation of Anti-Newcastle-Disease Serum.