A MYCOPLASMA STRAIN F38 GROWTH-INHIBITING MONOCLONAL-ANTIBODY (WM-25)IDENTIFIES AN EPITOPE ON A SURFACE-EXPOSED POLYSACCHARIDE ANTIGEN

Monoclonal antibody (MAb) WM-25 differentiates by in vitro growth inhi bition Mycoplasma capricolum subsp, capripneumoniae (Mycoplasma strain F38), which causes contagious caprine pleuropneumonia, from other Myc oplasma spp. (F. R. Rurangirwa, T. C. McGuire, A. J. Musoke, and A. Ki bor, Infect, Immun. 55:3219-3220, 1987), The antigen identified by MAb WM-25 was isolated from solubilized Mycoplasma strain F38 organisms b y MAb WM-25 affinity chromatography and was stained with Schiff's reag ent, but not with Coomassie blue, after separation by sodium dodecyl s ulfate polyacrylamide gel electrophoresis, Treatment of purified F38 p olysaccharide with periodate abolished binding with MAb WM-25, and MAb WM-25 binding was blocked with laminarin, a complex oligosaccharide w ith beta(1-->3) sugar linkages, Purified F38 polysaccharide blocked bo th growth inhibition and agglutination of live F38 organisms caused by MAb WM-25 and rabbit antiserum to F38 organisms. The results in this paper demonstrate that MAb WM-25 binds a periodate-sensitive epitope o n the F38 polysaccharide which is also exposed on the surface of Mycop lasma strain F38, Because MAb WM-25 also causes in vitro growth inhibi tion of F38, the reactive polysaccharide epitope may induce protective immune responses.