Standardized Assay for Clostridium botulinum Toxins

Abstract

To improve the accuracy and precision of the mouse assay for botulinum toxins found in foods and body fluids, a stable reference standard of botulinum toxin has been developed. It contains 100 ng crystalline type A botulinum toxin/ml 0.05M pH 4.2 sodium acetate buffer which contains 3 mg bovine serum albumin and 2 mg gelatin/ml. The albumin and gelatin stabilize the toxin. For distribution to laboratories carrying out the assay, 0.5 ml of the standard is sealed in 1 ml glass vials. The standard reference toxin, used as directed, enables the assayer to establish the response of laboratory mice, under a specific set of conditions, to a definite amount of toxin and to express the toxin content of an unknown in terms of ng toxin/g or ml food or body fluid. The mouse assay by itself is not specific for botulinum toxin, but when used in conjunction with specific antisera for identification and typing, it is the most reliable test available.