Preliminary Characterization of Cell-free K99 Antigen Isolated from Escherichia coli B41

Abstract

The K99 antigen of E. coli B41 was isolated by isoelectric precipitation from heated bacterial suspensions. Chromatography and immunoabsorption experiments suggested that the mannose-resistant hemagglutinating activity of partially purified preparations of antigen was K99. The antigen was partially susceptible to bacterial proteases and was inactivated by periodate oxidation. Hemagglutination inhibition experiments with sugars and absorption of K99 with [rabbit] antisera to human blood groups A and B substances suggested that K99 contains a terminal .alpha.-linked N-acetylgalactosamine moiety, which is involved in the hemagglutination reaction, and an adjacent terminal .alpha.-linked galactose moiety, which plays no part in the reaction.