Characterization of the strain-specific and common surface antigens of Mycoplasma arginini

A combination of quantitative immunoelectrophoresis and sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis was used to determine location and molecular weights of surface membrane antigens of four strains of Mycoplasma arginini. Two major surface antigens were identified for M. arginini by absorption of antiserum with whole cells: one surface antigen was strain specific, electrophoretically fast, and prominently located on the surface, whereas the other surface antigen was common to the four strains and of intermediate electrophoretic mobility. Three of the four strains of M. arginini (G-230, 23243, and 27389) possessed immunologically strain-specific antigens which did not cross-react, whereas the leonis strain lacked an immunologically detectable unique surface antigen. A monospecific antiserum prepared against immune precipitates of the strain-specific antigen of strain G-230 detected three polypeptides of 74,000, 44,000, and 17,000 daltons in SDS-polyacrylamide gels of membrane preparations. All four strains shared the common surface antigen which appeared considerably more hydrophobic than the strain-specific surface antigen because it could only be demonstrated by charge-shift immunoelectrophoretic conditions (addition of deoxycholate to the nonionic detergent). Monospecific antiserum to the common antigen of strain G-230 reacted with all four M. arginini strains, but did not react with two other arginine-utilizing species, and recognized three polypeptides of 40,000, 29,000, and 20,000 daltons in membranes of strain G-230. Whereas the common surface antigen is a likely target for conventional serological reactions used for identification of the species M. arginini, strain-specific antigen cannot fulfill this role but must participate in other surface reactions.