Antigenic differences within the speciesMycoplasma hominis

Abstract

SUMMARYMembrane and soluble fractions of one genital and two oral strains ofMycoplasma hominiswere compared by immunodiffusion and polyacrylamide gel electrophoresis. Differences were demonstrated between the membrane antigens of the three strains by immunodiffusion, and the membrane proteins also gave dissimilar patterns in polyacrylamide gel electrophoresis. The soluble fractions gave identical lines in immunodiffusion tests and similar patterns in polyacrylamide gel electrophoresis.When the strains were cross-titrated in metabolic inhibition (MI) and indirect haemagglutination (IHA) tests, statistical analysis of the results revealed significant differences between the strains. Previously, growth-inhibition, MI and IHA activity was shown to be associated with the membrane antigens ofM. hominis, so the intraspecies differences revealed by MI and IHA correlate with the differences in the membrane antigens demonstrated by immunodiffusion. Growth-inhibition tests, which might also have been expected to show intraspecies differences, did not do so, probably because of the insensitivity of the test. In contrast to MI and IHA, complement-fixation (CF) tests revealed a high degree of relatedness between the strains. This is consistent with the observation that the soluble antigens ofM. hominisparticipate in the CF reaction, and that the soluble antigens of different strains are identical in immunodiffusion tests.