Occurrence and properties of Haemophilus avium hemagglutinin

Hemagglutination studies on Haemophilus avium were done, using chicken RBC. Direct hemagglutinin was found in H avium cultured in solid medium. Hemagglutination ability was inactivated by heating and with formalin, but was not affected by sonication and by freezing and thawing. Serologic differences between H avium and H paragallinarum were verified by the hamagglutination-inhibition test.