[Allergic diagnosis of bovine brucellosis. 1. Conditions for the use of a purified protein allergen: brucellin (author's transl)].

A protein allergen extracted from the rough strain Brucella melitensis B 115, prepared for the diagnosis of Brucellosis, has been evaluated in cows. Injected in non infected and non vaccinated cows, this allergen does not give any reaction, does not sensitize for subsequent injections, does not give rise to antibodies detected by routine serologic tests, and thus does not interfere with usual screening. In cows, sensitized by injections of H 38 or 45/20 vaccines, the intradermal injection produces a delayed hypersensitivity reaction. The recommanded dose was determined to be 100 microgram and the reaction must be read at 72 hours. The most suitable sites of injection are the neck or the tail fold. It appears likely that allergic testing could not be employed for diagnosis in cows vaccinated with H 38 or 45/20 vaccines. Allergic testing is useful in cows which have been given strain 19 vaccine at least two years previously.