Hemagglutination by Bordetella bronchiseptica

A total of 53 isolates of Bordetella bronchiseptica from dogs and pigs were tested for their ability to agglutinate chicken, horse, sheep, dog, pig, and guinea pig erythrocytes. No differences in hemagglutinating activity were attributed to the animal origin of the bordetella isolates. Horse and dog erythrocytes consistently resulted in the strongest hemagglutination reactions, whereas only 4% of the B. bronchiseptica isolates produced weak agglutination of chicken erythrocytes. A total of 85% of the isolates agglutinated horse, sheep, dog, pig, and guinea pig erythrocytes. One canine isolate with hemagglutinating activity, strain 110H, was examined to determine the nature of the hemagglutinin(s) involved. Hemagglutination was always accompanied by hemadsorption, as determined by dark-field or phase-contrast microscopy. Treatment of cells and cell extracts with heat or protease K inhibited the hemagglutination reaction. Sonicated bacterial cells had a greater hemagglutinating ability than did unsonicated live bacteria. The hemagglutination reaction was not inhibited by any of 17 sugars nor by N- acetylglucosamine or ethylene glycol-bis-(beta-aminoethyl ether)-N, N-tetraacetic acid. Hemagglutinins were not detected in sonic extracts nor in several bacterial subunit fractions, including isolated pili. Antigens in some of these preparations were, however, detectable by indirect hemagglutination with anti-B. bronchiseptica serum. Isolated pili could not be detected on the erythrocyte surface by electron microscopy; however, serial sections of erythrocytes agglutinated by the live Bordetella organisms showed that the bacterial outer membrane and the erythrocyte surface were separated by a space of approximately 20 nm. This study provided additional circumstantial evidence that B. bronchiseptica pili or at least heat-labile surface proteins which extend some distance from the bacterial surface are involved in hemagglutination. Multiple hemagglutinins are likely to exist within this species since one isolate lacking pili also agglutinated canine erthyrocytes. The hemagglutinins of B. bronchiseptica need to be isolated and characterized before the hemagglutination reaction can be applied to studies of attachment.