Ellen R P, Fillery E D, Chan K H, Grove D A
Infect Immun. 1980 Feb;27(2):335-43. doi: 10.1128/iai.27.2.335-343.1980.
Laboratory strains representing six numerical taxonomy clusters and fresh isolates of human Actinomyces viscosus and Actinomyces naeslundii were studied by standard flocculation slide tests for the ability to hemagglutinate erythrocytes (RBC) from various animal species. Human AB and horse RBC were agglutinated more frequently and rapidly than others; guinea pig RBC were agglutinated by only a few strains. Human AB RBC were selected for studies of hemagglutination mechanisms. Treatment of RBC with clostridial neuraminidase (NTRBC) greatly enhanced hemagglutination for almost all strains. In hapten inhibition experiments in which various concentrations of sugars were used, beta-galactosides were the most effective inhibitors of hemagglutination for both RBC and NTRBC; inhibition of NTRBC agglutination required higher concentrations. Soybean lectin agglutinated both RBC and NTRBC but not Actinomyces cells. NTRBC agglutinated at a 125-fold-lower concentration. Hemagglutination was sensitive to ethylenediaminetetraacetate for one strain tested. Hemagglutination reactions were reversible by addition of beta-galactosides. The ability of Actinomyces strains to "prime" RBC for hemagglutination by removing sialic acid to expose more penultimate beta-galactoside sites was studied by recycling Actinomyces-agglutinated RBC which were dispersed with a lactose solution and washed free of bacteria (primed RBC). Priming in this manner augmented subsequent hemagglutination by indicator Actinomyces strains and made the RBC more sensitive to agglutination by soybean lectin. The priming ability of Actinomyces strains generally correlated with the amount of sialic acid removed from primed RBC. Strains representing the numerical taxonomy clusters differed in both their hemagglutinating and priming activities. Cluster 5 strains (typical A. naeslundii) were good agglutinators of RBC, NTRBC, and primed RBC but were poor primers. Cluster 3 strains (atypical A. naeslundii) were the weakest hemagglutinators but could prime RBC adequately for subsequent agglutination by other strains. Together, these data indicate that Actinomyces hemagglutination proceeds via a two-step mechanism: (i) neuraminidase removal of terminal sialic acid and (ii) lectin-like binding to exposed beta-galactoside-associated sites on the RBC. Strains differ in the extent to which they can perform the two functions, and this specificity may relate to their taxonomic classification.
通过标准的絮凝玻片试验，对代表六个数值分类学簇的实验室菌株以及人类粘性放线菌和内氏放线菌的新鲜分离株进行了研究，以检测它们对来自各种动物物种的红细胞（RBC）进行血凝的能力。人类AB型红细胞和马红细胞比其他红细胞更频繁、更快速地被凝集；豚鼠红细胞仅被少数菌株凝集。选择人类AB型红细胞进行血凝机制研究。用梭菌神经氨酸酶处理红细胞（NTRBC）后，几乎所有菌株的血凝作用都大大增强。在使用不同浓度糖类的半抗原抑制实验中，β-半乳糖苷是对红细胞和NTRBC血凝作用最有效的抑制剂；抑制NTRBC凝集需要更高的浓度。大豆凝集素能凝集红细胞和NTRBC，但不能凝集放线菌细胞。NTRBC在低125倍的浓度下就能凝集。对于所测试的一个菌株，血凝作用对乙二胺四乙酸敏感。通过添加β-半乳糖苷，血凝反应是可逆的。通过回收用乳糖溶液分散并洗去细菌的经放线菌凝集的红细胞（致敏红细胞），研究了放线菌菌株通过去除唾液酸以暴露出更多倒数第二个β-半乳糖苷位点来“致敏”红细胞以进行血凝的能力。以这种方式致敏增强了指示放线菌菌株随后的血凝作用，并使红细胞对大豆凝集素的凝集更敏感。放线菌菌株的致敏能力通常与从致敏红细胞中去除的唾液酸量相关。代表数值分类学簇的菌株在血凝和致敏活性方面存在差异。第5簇菌株（典型的内氏放线菌）是红细胞、NTRBC和致敏红细胞的良好凝集剂，但致敏能力较差。第3簇菌株（非典型的内氏放线菌）是最弱的血凝剂，但能充分致敏红细胞以供其他菌株随后凝集。总之，这些数据表明放线菌的血凝作用通过两步机制进行：（i）神经氨酸酶去除末端唾液酸；（ii）类似凝集素的物质与红细胞上暴露的β-半乳糖苷相关位点结合。不同菌株在执行这两种功能的程度上存在差异，这种特异性可能与其分类学分类有关。
