Characterization of membrane and cytoplasmic antigens of Mycoplasma arginini by two-dimensional (crossed) immunoelectrophoresis.

Two-dimensional immunoelectrophoresis was employed to electrophoretically identify membrane and cytoplasmic antigens of Mycoplasma arginini G-230. Five distinct cytoplasmic antigens were observed in soluble fractions prepared by digitonin lysis with electrophoretic mobilities (relative to bovine albumin) ranging from 0.36 to 0.86; four of these were common to other M. arginini strains: leonis and 23243. Five membrane antigens were identified, two of which (0.4 and 0.2) were common to the other M. arginini strains. The most prominent antigenic component of the membrane fraction (the complex membrane antigen) was electrophoretically heterogeneous, showing four antigenically related components with electrophoretic mobilities of 1.2, 0.95 to 0.76 and 0.05. The complex membrane antigen was exposed on the outside of the mycoplasmic cell because absorption of antiserum with live organisms removed antibody to this component. Antibodies to two other membrane components (0.6 and 0.2) were removed by absorption with Triton-solubilized membranes, but not by untreated membranes, indicating that these components were, at best, little exposed on either membrane surface. Antiserum was prepared against the complex membrane antigen using precipitin lines from two dimensional electropherograms as the immunogen. This antiserum reacted only with the complex membrane antigen and did not react with the other M. arginini strains, indicating that the complex membrane antigen was unique to strain G-230.