Mouse breeds and the toxicity test for pertussis vaccine

Mice from 14 suppliers (breeders) responded significantly different in the mouse-weight-gain test for toxicity of pertussis vaccine. Seven-day weight gain varied by 2.4 fold (2.5 to 6.1 g) and did not correlate with normal gain. Weight gain expressed as percentage-weight gain of the control varied by two-fold (52 to 104%). The percentage-weight gain requirement of greater than 60% (The Netherlands) was more discriminatory between mouse breeds than was the requirement of greate than or equal to 3.0 g gain (U.S.A.). Percentage-weight gains greater than 60%, however, showed significant distinctions. Specifications for the mice for this test are needed. Suggestions for the selection of the mouse are given.