Ciliostasis and loss of cilia induced by Mycoplasma hyopneumoniae in porcine tracheal organ cultures.

In vivo- and in vitro-grown Mycoplasma hyopneumoniae organisms were inoculated onto newborn piglet tracheal organ cultures to provide a model for interaction of this organism with ciliated respiratory epithelium. Ciliostasis and loss of cilia in tracheal rings were induced by M. hyopneumoniae grown in vivo and with low-passage cultures when grown in vitro. Levels of calmodulin or dehydrogenase enzymes in tracheal ring epithelium were not altered even though ciliostasis and loss of cilia induced by M. hyopneumoniae were extensive. The capacity for inducing epithelial damage diminished with in vitro passage of the organism. Attempts to induce higher-passage cultures to attach to cilia, cause ciliostasis, or cause ciliary damage by supplementation of mycoplasmal medium with porcine lung extract failed. Epithelial damage induced by M. hyopneumoniae in tracheal rings was averted by using porcine immune serum or by separating the organisms from ciliated epithelium with a 0.1-microns-pore-size membrane. Attachment, or at least close association, of M. hyopneumoniae to ciliated epithelium appeared to be necessary to induce ciliostasis and loss of cilia in this model.

Heterogeneity among strains of Mycoplasma granularum and identification of Mycoplasma hyosynoviae, sp. n.

Twelve filtrable, pleomorphic organisms isolated from swine joints and respiratory tracts had typical colonial and microscopic characteristics of mycoplasmas. They resisted penicillin and did not revert to cell wall-producing bacterial forms in media devoid of bacterial inhibitors. The morphological and growth characteristics of these mycoplasmas were similar to those described previously for Mycoplasma granularum. However, a new name, M. hyosynoviae, is proposed for them since they differed biologically, serologically, and electrophoretically from the prototype strain of M. granularum. M. hyosynoviae required sterols, was stimulated by gastric mucin, and metabolized arginine; however, it did not metabolize urea, ferment glucose, or reduce tetrazolium. The organism produced "film and spots" on horse serum-supplemented medium and produced alpha hemolysis of guinea pig and sheep erythrocytes; however, it did not digest serum, produce phosphatase, or hemadsorb guinea pig or swine erythrocytes. M. hyosynoviae was distinguished from three other swine mycoplasmas, M. granularum, M. hyorhinis, and M. laidlawii, by means of acrylamide gel electrophoresis, growth inhibition, metabolic inhibition, and immunodiffusion techniques. It was also serologically and electrophoretically distinct from 13 additional non-swine mycoplasmas which require sterols and metabolize arginine.