Immunogenicity of Moraxella bovis hemolysin

Anti-Moraxella bovis hemolysin activity was observed in 35 cattle exposed to field infections of infectious bovine keratoconjunctivitis (IBK). All cattle in infected herds seroconverted with respect to antihemolysin whether or not clinical IBK was noted. Cattle previously exposed to IBK possessed higher antihemolysin titers than did younger, nonexposed cattle. Antihemolysin activity was noted in bovine sera up to 7 years after exposure to IBK. Sera from experimentally infected calves were found to possess antihemolytic activity against all 33 strains of M bovis tested. Antihemolytic activity could be demonstrated in random-bred mice inoculated with whole doxycycline-treated M bovis, frozen or lyophilized whole M bovis, and membrane fractions treated with sodium lauryl sarcosinate, Triton X 100, and Triton X 100 + EDTA, but not with formalin-treated whole M bovis.