A genital strain of Mycoplasma hominis was fractionated by differential centrifugation after disruption of the cells by alternate cycles of freezing and thawing, by gas cavitation under nitrogen, or by ultrasonic treatment.
Antigens of the cell membrane were distinct from those in the soluble cell contents, judging from metabolic inhibition (MI), indirect haemagglutination (IHA), gel-diffusion and immunoelectrophoresis tests, and by the antibody response in rabbits inoculated with these fractions. The antigens which gave rise to MI and IHA antibody were located in the cell membrane.
Extraction of whole cells of M. hominis by various chemical methods suggested that the active components were protein in nature and that there was no lipid hapten, as in M. pneumoniae, or polysaccharide, as in M. mycoides var. mycoides.
This work was partly supported by a Medical Research Council grant, which provided the remuneration of MRH.
We thank Professor R. A. Kekwick and Dr J. M. Creeth of the Biophysics Department of this Institute for their advice on the processing of plasma and density gradient centrifugation, and Mr F. C. Belton of the Microbiological Research Establishment, Porton, Wilts, for growing a 50 litre batch of M. hominis.