Cádiz Leandro, Torres Alexia, Valdés Raúl, Vera Gabriel, Gutiérrez Daniela, Levine Myron M, Montero David A, O'Ryan Miguel, Rasko David A, Stine O Colin, Vidal Roberto, Del Canto Felipe
Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
Front Microbiol. 2018 Oct 16;9:2463. doi: 10.3389/fmicb.2018.02463. eCollection 2018.
The coli surface antigen 26 (CS26) of enterotoxigenic (ETEC) had been described as a putative adhesive pilus based on the partial sequence of the gene, detected in isolates from children with diarrhea in Egypt. However, its production and activity as adherence determinant has not been experimentally addressed. The was identified as a homolog of genes encoding structural subunits of ETEC colonization factors (CFs) CS12, CS18, and CS20. These CFs, along with the recently discovered CS30, belong to the γ family of pili assembled by the chaperone-usher pathway (CU pili). Further, the complete CS26 locus, , was described in an O141 ETEC strain (ETEC 100664) obtained from a diarrhea case in The Gambia, during the Global Enterics Multicenter Study. Here, we report that CS26 is a pilus of ∼10 nm in diameter, with the capacity to increase the cell adherence of the non-pathogenic strain DH10B. As for other related pili, production of CS26 seems to be regulated by phase variation. Deletion of in ETEC 100664 significantly decreased its adherence capacity, which was recovered by complementation. Furthermore, CrsH was cross-recognized by polyclonal antibodies directed against the major structural subunit of CS20, CsnA, as determined by Western blotting and immunogold labeling. ETEC CS26+ strains were found to harbor the heat-labile enterotoxin only, within three different sequence types of phylogroups A and B1, the latter suggesting acquisition through independent events of horizontal transfer. Overall, our results demonstrate that CS26 is an adhesive pilus of human ETEC. In addition, cross-reactivity with anti-CsnA antibodies indicate presence of common epitopes in γ-CFs.
产肠毒素大肠杆菌（ETEC）的大肠杆菌表面抗原26（CS26），基于该基因的部分序列，曾被描述为一种假定的黏附菌毛，该序列在埃及腹泻儿童的分离株中被检测到。然而，其作为黏附决定因素的产生和活性尚未经过实验验证。该基因被鉴定为编码ETEC定植因子（CFs）CS12、CS18和CS20结构亚基的基因的同源物。这些CFs，连同最近发现的CS30，属于通过伴侣-usher途径组装的菌毛γ家族（CU菌毛）。此外，在全球肠道多中心研究期间，从冈比亚的一例腹泻病例中获得的一株O141 ETEC菌株（ETEC 100664）中描述了完整的CS26基因座。在此，我们报告CS26是一种直径约为10 nm的菌毛，具有增加非致病性菌株DH10B细胞黏附的能力。至于其他相关菌毛，CS26的产生似乎受相变调控。在ETEC 100664中缺失该基因座会显著降低其黏附能力，通过该基因座的互补可恢复黏附能力。此外，通过蛋白质印迹和免疫金标记确定，CrsH被针对CS20主要结构亚基CsnA的多克隆抗体交叉识别。发现ETEC CS26+菌株仅携带热不稳定肠毒素，存在于系统发育组A和B1的三种不同序列类型中，后者表明是通过水平转移的独立事件获得的。总体而言，我们的结果表明CS26是人类ETEC的一种黏附菌毛。此外，与抗CsnA抗体的交叉反应表明γ-CFs中存在共同表位。
