Abstract
The agglutinability of 54 strains of Bact. abortus prepared as monovalent antigens and one polyvalent antigen has been studied. Bovine sera showing a large variation in agglutinin content have been employed.
In these studies there was no significant variation in the agglutinability of the monovalent antigens. Any of the cultures would have been suitable for the production of antigen for use in the diagnosis of Bang's disease. There was no advantage or disadvantage in favor of any of the monovalent antigens as compared with the polyvalent antigen. The one polyvalent antigen used was prepared from 8 strains of Bact. abortus, all of which were isolated from cattle. The 54 cultures varied in age of cultivation on artificial media from 13 years to a few days. Thirty-nine were isolated at the Minnesota Experiment Station. Four originated in Pennsylvania. Four were received from Connecticut, 3 from New Zealand, one (No. 80) was isolated in California, and one more was received from California that had been isolated in Oregon but cultivated in California for several years, one from New York, and one from Oregon. Of the 39 isolated at Minnesota, 32 were from cattle, 5 from horses, and 2 from swine. Those from cattle were isolated from whole milk, colostrum, placenta, vaginal discharges, foetal lung, foetal stomach contents and from enlarged joints. In one case 4 cultures were isolated from the same animal but from different tissues or fluids. One of the cultures isolated from a bovine was classified by Huddleson as Para-abortus.
In preliminary studies, sera from 97 cattle were used, 14 of which showed high agglutinin content, 15 showed medium agglutinin content, 24 had a very low titre, and 44 negative sera with no agglutinin content.
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