Enterotoxigenic Escherichia coli (ETEC) strains are important pathogens for humans and farm animals such as pigs. Porcine ETEC strains induce diarrhea through the production of heat-labile enterotoxin (LT) and/or heat-stable enterotoxins (pSTa/STb). Although LT secretion levels differ between porcine ETEC strains, and this has been linked to virulence, it is unclear whether ST secretion levels also differ between porcine ETEC strains. In addition, the molecular mechanism underlying different LT secretion levels has not been elucidated. In this work, multiple porcine ETEC strains were assessed for their capacity to produce and secrete the enterotoxins LT, pSTa, and STb. The strains differed greatly in their capacity to secrete LT, pSTa, and STb. Remarkably, in some strains, periplasmic production did not correlate with their ability to secrete LT, resulting in high periplasmic production and low LT secretion levels. Furthermore, the results indicated that the type II secretion system (T2SS) protein YghG plays a regulatory role in controlling LT secretion levels. These findings highlight YghG as an important mediator of the secretion of the heat-labile enterotoxin LT by porcine ETEC strains and provide better insights into ETEC enterotoxin secretion.

中文翻译：

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猪产肠毒素大肠杆菌菌株通过不同的 YghG 水平分泌肠毒素的能力不同。

产肠毒素大肠杆菌(ETEC) 菌株是人类和猪等农场动物的重要病原体。猪 ETEC 菌株通过产生不耐热肠毒素 (LT) 和/或热稳定肠毒素 (pSTa/STb) 引起腹泻。尽管猪 ETEC 菌株之间的 LT 分泌水平不同，这与毒力有关，但尚不清楚猪 ETEC 菌株之间的 ST 分泌水平是否也不同。此外，不同LT分泌水平的分子机制尚未阐明。在这项工作中，评估了多种猪 ETEC 菌株产生和分泌肠毒素 LT、pSTa 和 STb 的能力。这些菌株在分泌 LT、pSTa 和 STb 的能力方面差异很大。值得注意的是，在某些菌株中，周质产生与其分泌 LT 的能力无关，导致高周质产量和低 LT 分泌水平。此外，结果表明 II 型分泌系统 (T2SS) 蛋白 YghG 在控制 LT 分泌水平方面发挥调节作用。这些发现突出了 YghG 作为猪 ETEC 菌株分泌不耐热肠毒素 LT 的重要介质，并提供了对 ETEC 肠毒素分泌的更好见解。