A tissue culture system to study respiratory ciliary epithelial adherence of selected swine mycoplasmas

An in vitro culture system for swine tracheal epithelial cells was develope d to study the adherence of swine mycoplasmas. Swine tracheal epithelial ce lls were isolated by enzymatic digestion and cultured on microporous membra nes. Growth medium was placed under the membrane support to create air-liqu id interface feeding resulting in the cells growing cilia and microvilli on the apical surface. Two strains of Mycoplasma hyopneumoniae (pathogenic st rain 91-3 and non-pathogenic type strain J) and two strains of Mycoplasma f locculare (type strain Ms42 and field isolate 7160T) were used in this stud y. The morphology of the cultured tracheal cells was evaluated by transmiss ion electron microscopy. Adherence of M. hyopneumoniae and M. flocculare an d damage to the cilia were demonstrated using scanning electron microscopy. The pathogenic M. hyopneumoniae strain 91-3 adhered to cilia inducing obvio us damage. The non-pathogenic M. hyopneumoniae strain J did not adhere to m ature cilia. Both M. flocculare strains Ms42 and 7160T adhered to mature an d budding cilia. No obvious ciliary damage was observed with strain Ms42. M inimal damage consisting of a slight tangling of the cilia occurred after a dherence by strain 7160T. This model will enable us to further study the Po le of adherence of mycoplasmas on the pathogenesis of swine pneumonia. (C) 2000 Elsevier Science B.V. All rights reserved.