Francis D H, Erickson A K, Grange P A
Department of Veterinary Science, South Dakota State University, Brookings 57007-1396, USA.
Adv Exp Med Biol. 1999;473:147-54. doi: 10.1007/978-1-4615-4143-1_13.
The three antigenic variants of the K88 fimbrial adhesin (K88ab, K88ac, and K88ad) of enterotoxigenic Escherichia coli (ETEC) each exhibit unique specificity with regard to their hemagglutination characteristics. The variants are also unique in the specificity of their binding to the brush borders of enterocytes isolated from pigs with different genetic backgrounds. Diversity in enterocyte binding specificity suggests the existence of several K88 receptors, expressed individually or in various combinations on porcine enterocytes. Three candidate receptors have been identified that may explain the adhesion of K88 fimbrial variants to various porcine enterocytes. These receptors are an intestinal mucin-type sialoglycoprotein (IMTGP), an intestinal transferrin (GP74), and an intestinal neutral glycosphingolipid (IGLad). The IMTGP binds K88ab and K88ac, but not K88ad. The GP74 binds K88ab, but not K88ac or K88ad, and the IGLad binds K88ad, but not K88ab or K88ac. Each of the candidate receptors has been found in brush borders that are adhesive for the fimbriae that bind the respective receptor. They have not been found in brush borders that are not adhesive for those same fimbriae. The presence of IMTGP was highly correlated with susceptibility of neonatal gnotobiotic pigs to ETEC expressing K88ab or K88ac.
产肠毒素大肠杆菌（ETEC）的K88菌毛黏附素的三种抗原变体（K88ab、K88ac和K88ad）在血凝特性方面各自表现出独特的特异性。这些变体在与从不同遗传背景的猪分离的肠上皮细胞刷状缘结合的特异性方面也具有独特性。肠上皮细胞结合特异性的多样性表明存在几种K88受体，它们在猪肠上皮细胞上单独或组合表达。已经鉴定出三种候选受体，它们可能解释K88菌毛变体与各种猪肠上皮细胞的黏附。这些受体是一种肠道黏蛋白型唾液糖蛋白（IMTGP）、一种肠道转铁蛋白（GP74）和一种肠道中性糖鞘脂（IGLad）。IMTGP结合K88ab和K88ac，但不结合K88ad。GP74结合K88ab，但不结合K88ac或K88ad，而IGLad结合K88ad，但不结合K88ab或K88ac。已经在与结合相应受体的菌毛具有黏附性的刷状缘中发现了每种候选受体。在对相同菌毛不具有黏附性的刷状缘中未发现它们。IMTGP的存在与新生无菌猪对表达K88ab或K88ac的ETEC的易感性高度相关。
