The Second International Standard for anti-Brucella abortus serum.

In 1965, the WHO Expert Committee on Biological Standardization (1966) noted that stocks of the International Standard for Anti-Brucella abortus Serum were almost exhausted and requested the Central Veterinary Laboratory, Weybridge, England, to examine a quantity of serum offered by that laboratory for its suitability to serve as a replacement, and to arrange a collaborative assay. After being distributed into ampoules and freeze-dried, the serum was assayed against the International Standard by 17 laboratories in 12 countries. On the basis of the results obtained, the serum has been established as the Second International Standard for Anti-Brucella abortus Serum and the International Unit has been defined as the activity contained in 0.09552 mg of the Second International Standard.