The pathogenesis of respiratory infection of lambs by mycoplasmas

Abstract

Conclusions M. ovipneumoniae expresses a polysaccharide capsule with variable size expression in different cultures. Strain heterogeneity could be further indicated by variable reactivity of this capsular material with several different lectins. Morphological observations suggest that this capsule facilitates adherence of the organism to ciliated epithelium. Clinical Relevance Strain variation associated with this capsule and its possible association with attachment to cilia may provide a versatile interaction of M. ovipneumoniae with its environment; thus, a long term colonization of the host by the organism. different isolates. Light and electron microscopic examinations of infected tracheal rings revealed disorganization and sloughing of the epithelium, and association of mycoplasmas only with the cilia. Following repeated in vitro passages, the organisms had reduced ability to inhibit ciliary activity which correlated with decreased hydrogen peroxide production. Addition of catalase to the organ cultures delayed loss of ciliary activity. Conclusions M. ovipneumoniae induced ciliostasis in ovine tracheal ring explants which correlated with hydrogen peroxide production. M. ovipneumoniae is an extracellular pathogen that colonizes the ciliated epithelium. Clinical relevance M. ovipneumoniae colonization of respiratory epithelial cells contributes to the pathogenesis of sheep respiratory disease.