Exposure of bovine cornea to different strains of Moraxella bovis and to other bacterial species in vitro.

A collection of strains of Moraxella bovis, some pathogenic and some non-pathogenic in cattle, together with other M. bovis preparations, Neisseria ovis, Staphylococcus aureus and Moraxella non-liquefaciens were studied by scanning electron microscopy for their affinity to bovine corneal preparations in vitro. The in vitro procedure provides a convenient method for studies on host-pathogen interactions at the early stage of pathogenesis. The results corresponded well with the pathogenicity of the respective strains and species in cattle. It is considered that the pathogenicity of M. bovis is associated with at least two factors, piliation and the ability to produce pit-like depressions in corneal epithelial cells. The other bacterial species, which are not thought to play an important role in infectious bovine keratoconjunctivitis, had the ability to adhere to the bovine cornea but did not produce pits. The pitting factor of M. bovis is of interest in relation to studies on vaccination against infectious bovine keratoconjunctivitis.