Characterization of hemolysin of Moraxella bovis using a hemolysis-neutralizing monoclonal antibody

A concentrated bacterial culture supernatant from the hemolytic Moraxella b ovis strain UQV 148NF was used to immunize mice and generate monoclonal ant ibodies (MAbs), One, MAb G3/D7, neutralized the hemolytic activity of M. bo vis and recognized a 94-kDa protein by Western blot analysis in hemolytic M . bovis strains representing each of the different fimbrial serogroups, Exp osure of corneal epithelial cells to ill, bovis concentrated culture supern atants demonstrated a role for an exotoxin in the pathogenesis of infectiou s bovine keratoconjunctivitis, while neutralization of hemolytic and cytoto xic activities by MAb G3/D7 implies that these activities are related or ha ve common epitopes, The action of M. bovis hemolysin was further characteri zed in sheep erythrocyte preparations with a binding step and Ca2+ required for lysis to proceed, similar to the RTX family of bacterial exotoxins. Ne utralization of lytic activity in vitro is evidence for the presence of M. bovis antigens, which may be capable of protecting cattle from the developm ent of infectious bovine keratoconjunctivitis.