GLYCOLIPID RECEPTORS FOR ATTACHMENT OF MYCOPLASMA-HYOPNEUMONIAE TO PORCINE RESPIRATORY CILIATED CELLS

Glycolipid receptors for Mycoplasma hyopneumoniae attachment were analyzed by using a thin-layer chromatography (TLC) overlay assay, M. hyopneumoniae bound specifically to sulfatide, globoside, and monosialoganglioside GM3. No binding to sphingomyelin, cerebroside, lactosyl ceramide, ceramide trihexoside, monosialogangliosides GM1 and GM2, disialogangliosides (GD1a, GD1b, and GD3), trisialoganglioside (GT1b), cholesterol, cholesterol sulfate, palmitic acid, tripalmitin, or cholesteryl palmitate was detected. Total lipids extracted from cilia of the swine respiratory epithelium, the natural targets of M. hyopneumoniae infection, were also separated on TLC plates and overlaid with mycoplasmas. M. hyopneumoniae bound specifically to three ciliary glycolipids identified as La, Lb, and Lc, Binding to Lc was stronger than to La and Lb. All three lipids were believed to be sulfated glycolipids, as determined by laminin binding and staining with azure A. Lc was identified as a putative sulfatide because it had a mobility similar to that of authentic sulfatide and comigrated with sulfatide on TLC plates. Laminin bound to La, Lb, and Lc and produced dose-dependent inhibition of adherence of the mycoplasma to the three ciliary receptors. Binding of the mycoplasma to sulfatide, La, Lb, and Lc was partially inhibited by dextran sulfate, heparin, fucoidan, mucin, and chondroitin sulfate B. These substances blocked the adherence of M. hyopneumoniae to cilia and ciliated tells as shown in a previous study (Q. Zhang, T. F. Young, and R. F, Ross, Infect. Immun, 62:1616-1622, 19944). These results indicate that La, Lb, and Lc are the major native receptors for M. hyopneumoniae adherence to ciliated cells.