Capsular material of Mycoplasma gallisepticum and its possible relevance to the pathogenic process.

A ruthenium red-staining capsule was observed on two pathogenic strains, but not on one nonpathogenic strain of Mycoplasma gallisepticum. The capsule appeared to mediate cytadsorption of mycoplasmas to the chicken tracheal epithelium without evidence of membrane fusion. No relationship was seen between the presence of capsule and hemagglutination titers of the strains examined.