[Hemagglutinating activity and morphology of antigen K 99 in enterotoxic strains of E. coli isolated from calves].

The hemagglutination activity and morphology of antigen K 99 in enterotoxic E. coli strains isolated from calves was studied. It was proven that antigen K 99 is produced not at 18 degrees C, but at 37 degrees C. All K 99+ E. coli strains react with absorbed anti K 99 serum, showing various anti-agglutination titers. The hemagglutination activity of K 99+ E. coli strains is inhibited by absorbed K 99 antiserum. In immunodiffuse tests all K 99+ E. coli strains react by producing a single precipitation line. It is proven electronmicroscopically that on the surface of the bacterial cell of K 99+ E. coli strains is observed a filamentous structure, consisting of numerous fine fibers which give it a fibriform outlook. No such morphological structures are observed in K 99- E. coli strains.