Postweaning diarrhea (PWD) is an economically important, multifactorial disease affecting pigs within the first 2 weeks after weaning. The most common agent associated with PWD is enterotoxigenic Escherichia coli (ETEC). Currently, antibiotics are used to control PWD, and this has most likely contributed to an increased prevalence of antibiotic-resistant strains. This puts pressure on veterinarians and farmers to decrease or even abandon the use of antibiotics, but these measures need to be supported by alternative strategies for controlling these infections. Naturally derived molecules, such as lactoferrin, could be potential candidates due to their antibacterial or immune-modulating activities. Here, we analyzed the ability of bovine lactoferrin (bLF), porcine lactoferrin (pLF), and ovotransferrin (ovoTF) to inhibit ETEC growth, degrade ETEC virulence factors, and inhibit adherence of these pathogens to porcine intestinal epithelial cells. Our results revealed that bLF and pLF, but not ovoTF, inhibit the growth of ETEC. Furthermore, bLF and pLF can degrade several virulence factors produced by ETEC strains, more specifically F4 fimbriae, F18 fimbriae, and flagellin. On the other hand, ovoTF degrades F18 fimbriae and flagellin but not F4 fimbriae. An in vitro adhesion assay showed that bLF, ovoTF, and pLF can decrease the number of bacteria adherent to epithelial cells. Our findings demonstrate that lactoferrin can directly affect porcine ETEC strains, which could allow lactoferrin to serve as an alternative to antimicrobials for the prevention of ETEC infections in piglets.

中文翻译：

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猪和牛乳铁蛋白抑制猪产肠毒素的大肠杆菌的生长并降解其毒力因子。

断奶后腹泻（PWD）是一种经济上重要的多因素疾病，在断奶后的前2周内会影响猪。与PWD相关的最常见药物是产肠毒素的大肠杆菌（ETEC）。当前，抗生素用于控制PWD，这很可能导致了抗生素耐药菌株的流行。这给兽医和农民带来了减少甚至放弃使用抗生素的压力，但是这些措施需要控制这些感染的替代策略的支持。天然来源的分子，例如乳铁蛋白，由于其抗菌或免疫调节活性，可能是潜在的候选者。在这里，我们分析了牛乳铁蛋白（bLF），猪乳铁蛋白（pLF）和卵转铁蛋白（ovoTF）抑制ETEC生长，降解ETEC毒力因子以及抑制这些病原体对猪肠上皮细胞粘附的能力。我们的结果表明，bLF和pLF抑制了ETEC的生长，而ovoTF没有。此外，bLF和pLF可以降解ETEC菌株产生的几种毒力因子，尤其是F4菌毛，F18菌毛和鞭毛蛋白。另一方面，ovoTF降解F18菌毛和鞭毛蛋白，而不降解F4菌毛。一个体外粘附试验表明，bLF，ovoTF和pLF可以减少粘附在上皮细胞上的细菌数量。我们的发现表明，乳铁蛋白可以直接影响猪的ETEC株，这可以使乳铁蛋白作为抗菌剂的替代品，以预防仔猪的ETEC感染。