MICROBIAL ANTIGENS ASSOCIATED WITH SPECIFIC ADHERENCE

1型菌毛介导的粘性放线菌T14 V对 唾液处理的羟基磷灰石（SHA）涉及脯氨酸的识别 获得性表膜中富含蛋白质，而2型菌毛介导的 菌株T14 V或A.内氏链球菌WVU 45 oralis 34依赖于Gal/GalNAc反应性菌毛凝集素。的基因 每个不同菌毛结构亚基编码533个蛋白质 至535个氨基酸残基，以30个可切割信号序列开始， 或32个残基。每个成熟亚基（M（r）约等于54，000） 主要是亲水性的，除了羧基末端片段， 被鉴定为潜在的跨膜结构域。不同 放线菌属菌毛亚基之间没有明显的同源性 包括革兰氏阴性菌菌毛蛋白在内的其他蛋白质， T14 V株的2型亚单位与 WVU 45（79%氨基酸序列相似性）和WVU 45之间的较低同源性 T14 V株的2型亚基和1型亚基（49%氨基酸 序列相似性）。2型菌毛凝集素受体 放线菌属在所有的S.口腔（12/12），但更少 对其他草绿色链球菌频繁或根本没有。抗原性 不同的线性多糖，每一种由不同的， 磷酸二酯连接的重复单元，被确定为受体 结构在S. oralis菌株34、10557和C104;温和J22。作为 与菌株34和J22，抗原性不同的结构研究 菌株10557和C104的受体多糖已经表明，它们的 寡糖重复单元具有Gal（beta）1->3GalNAc， GalNAc（beta）1->3Gal，分别位于凝集素的拟定位点 识别.这些结构中的每一个都与受体 特异性哺乳动物细胞表面糖蛋白和糖脂的活性， 细菌和宿主细胞受体之间的明显模仿提供了 抗体未能定向的可能解释 这些细菌多糖的受体区域。

Type 1 fimbriae-mediated adherence of Actinomyces viscosus T14V to saliva-treated hydroxyapatite (SHA) involves the recognition of proline rich proteins in the acquired pellicle whereas the type 2 fimbriae-mediated coaggregations of strain T14V or A. naeslundii WVU45 with Streptococcus oralis 34 depends on a Gal/GalNAc-reactive fimbrial lectin. The gene for the structural subunit of each different fimbria encoded a protein of 533 to 535 amino acid residues beginning with a cleavable signal sequence of 30 or 32 residues. Each mature subunit (M(r) equals about 54,000) was predominantly hydrophilic except for a carboxy terminal segment that was identified as a potential membrane spanning domain. The different Actinomyces spp. fimbrial subunits showed no significant global homologies with other proteins including the pilins of gram negative bacteria, but high homology was noted between the type 2 subunits of strains T14V and WVU45 (79% amino acid sequence similarity) and lower homology between either type 2 subunit and the type 1 subunit of strain T14V (49% amino acid sequence similarity). Receptors for the type 2 fimbrial lectin of Actinomyces spp. were detected on all strains of S. oralis (12/12) but less frequently or not at all on other viridans streptococci. Antigenically distinct linear polysaccharides, each composed of a different, phosphodiester linked repeating unit, were identified as the receptor structures on S. oralis strains 34, 10557 and C104 and S. mitis J22. As with strains 34 and J22, structural studies of the antigenically distinct receptor polysaccharides of strains 10557 and C104 have shown that their oligosaccharide repeating units have Gal(beta)1->3GalNAc and GalNAc(beta)1->3Gal, respectively, at the proposed site of lectin recognition. Each of these structures has been associated with the receptor activity of specific mammalian cell surface glycoproteins and glycoplipids, and the apparent mimicry between bacterial and host cell receptors provides a possible explanation for the failure of antibodies to be directed toward the receptor regions of these bacterial polysaccharides.