Purification and properties of Haemophilus paragallinarum hemagglutinin.

Hemagglutinin (HA) of Haemophilus paragallinarum was purified, and its immunologic, chemical, and morphologic properties were studied. The HA was purified by gel filtration on Sepharose 6B and by subsequent ultracentrifugation of trypsinized cells after pretreatment with neuraminidase. After gel filtration, the HA component (fractioned HA) gave 1 precipitin line by gel diffusion, and after inoculation in chickens, hemagglutinination-inhibition antibody to trypsin-sensitive HA antigen was found. Chickens inoculated with the fractionated HA were protected from challenge exposure with H paragallinarum. In a sample further purified by ultracentrifugation (purified HA), a single protein band was detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; it had a molecular weight of approximately 39,000. A molecular weight of several hundred thousand to several million was observed by gel filtration. Seemingly, HA of H paragallinarum is an aggregate of more than 20 HA sub-units. The purified HA included protein and some sugars, and according to electron microscopic observation, had a filamentous structure.