PRODUCTION OF BRUCELLA ALLERGENS AND EVALUATION OF THEIR BIOLOGICAL-ACTIVITY IN A GUINEA-PIG BIOASSAY

A study was conducted to evaluate the biological activity of Brucella allergens extracted with hydrochloride or trichloroacetic acid. Smooth and mucoid Brucella abortus cells and the medium in which brucellae w ere propagated were used to prepare the allergens. The biological acti vity of the allergens was estimated in guinea-pigs sensitized with Bru cella abortus strain 544. The guinea-pigs were intradermally injected with several allergen dilutions. The dilutions were coded and randomiz ed for site of injection so that none of the dilution was injected twi ce on the same site. Variance analysis using incomplete Latin square w as used for the statistical calculation of the results. The calculated biological activity of the allergens was compared with the biological activity of a 'standard' allergen that has proved effective in detect ing cattle brucellosis. The skin erythema diameter was best when recor ded 32 h after allergen injection. Statistical analysis of the skin er ythema diameters showed a great variation in biological activity (12-1 05%) between the allergens. Only the allergen extracted from the mediu m in which a mucoid Brucella strain was propagated was as potent as th e standard. The use of the incomplete Latin square for variance analys is resulted in the estimation of the biological activity of nine batch es of allergen in only 27 guinea-pigs.