Immunologic relationship between Page's and Sawata's serotype strains of Haemophilus paragallinarum

Immunologic relationship among Page's A, B, and C and Sawata's 1 and 2 serotype strains of Haemophilus paragallinarum was investigated. In cross-protection tests, two distinct type-specific immunities existed among the strains used. All Page's serotype A strains (083, W, Georgia, and Germany) were immunologically similar to Sawata's serotype 1 strain 221, although serotype C strain Modesto was similar to serotype 2 strain H-18. Cross-protection was not observed between these two serotypes. However, strains Spross and 0222 of serotype B lacked pathogenicity and protective antigenicity.