Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania, USA.
Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center, Agriculture Research Service, U.S. Department of Agriculture, Ames, Iowa, USA.
Microbiol Spectr. 2024 Nov 5;12(11):e0127024. doi: 10.1128/spectrum.01270-24. Epub 2024 Sep 27.
Shiga toxinproducing (STEC) are major foodborne pathogens that result in thousands of hospitalizations each year in the United States. Cattle, the natural reservoir, harbor STEC asymptomatically at the recto-anal junction (RAJ). The molecular mechanisms that allow STEC and non-STEC to adhere to the RAJ are not fully understood, in part because most adherence studies utilize human cell culture models. To identify a set of bovine-specific adherence factors, we used the primary RAJ squamous epithelial (RSE) cell-adherence assay to coculture RSE cells from healthy Holstein cattle with diverse strains from bovine and nonbovine sources. We hypothesized that a comparative genomic analysis of the strains would reveal factors associated with RSE adherence. After performing adherence assays with historical strains from the Reference Center ( = 62) and strains newly isolated from the RAJ ( = 15), we used the bioinformatic tool Roary to create a pangenome of this collection. We classified strains as either low or high adherence and using the Scoary program compiled a list of accessory genes correlated with the "high adherence" strains. While none of the correlations were statistically significant, several gene clusters were associated with the high-adherence phenotype, including two that encode uncharacterized proteins. We also demonstrated that non-STEC strains from the RAJ are more adherent than other isolates and can outcompete STEC in coculture with RSEs. Further analysis of adherence-associated gene clusters may lead to an improved understanding of the molecular mechanisms of RSE adherence and may help develop probiotics targeting STEC in cattle.
strains that produce Shiga toxin cause foodborne illness in humans but colonize cattle asymptomatically. The molecular mechanisms that uses to adhere to cattle cells are largely unknown. Various strategies are used to control in livestock and limit the risk of outbreaks. These include vaccinating animals against common strains and supplementing their feed with probiotics to reduce the carriage of pathogens. No strategy is completely effective, and probiotics often fail to colonize the animals. We sought to clarify the genes required for adherence in cattle by quantifying the attachment to bovine cells in a diverse set of bacteria. We also isolated nonpathogenic from healthy cows and showed that a representative isolate could outcompete pathogenic strains in cocultures. We propose that the focused study of these strains and their adherence factors will better inform the design of probiotics and vaccines for livestock.
产志贺毒素的（STEC）是美国每年导致数千人住院的主要食源性病原体。牛是其自然宿主，无症状地在直肠-肛门交界处（RAJ）携带 STEC。导致 STEC 和非 STEC 附着于 RAJ 的分子机制尚未完全了解，部分原因是大多数附着研究使用人类细胞培养模型。为了确定一组牛特异性附着因子，我们使用 RAJ 原始鳞状上皮（RSE）细胞附着测定法，将来自健康荷斯坦奶牛的 RSE 细胞与来自牛和非牛源的多种进行共培养。我们假设对这些菌株进行比较基因组分析将揭示与 RSE 附着相关的因素。在用历史菌株进行附着测定后（= 62）和新从 RAJ 分离的菌株（= 15），我们使用生物信息学工具 Roary 创建了该集合的泛基因组。我们将菌株分类为低附着或高附着，并使用 Scoary 程序编译与“高附着”菌株相关的辅助基因列表。虽然没有任何相关性具有统计学意义，但有几个基因簇与高附着表型相关，包括两个编码未表征蛋白的基因簇。我们还证明，来自 RAJ 的非 STEC 菌株比其他分离株更具附着性，并且可以在与 RSE 的共培养中与 STEC 竞争。对附着相关基因簇的进一步分析可能会导致对 RSE 附着的分子机制的更好理解，并可能有助于开发针对牛 STEC 的益生菌。
产生志贺毒素的菌株会导致人类食源性疾病，但在无症状的情况下在牛中定植。用于附着牛细胞的分子机制在很大程度上是未知的。各种策略用于控制牲畜中的并限制疫情爆发的风险。这些策略包括针对常见菌株对动物进行疫苗接种和用益生菌补充它们的饲料以减少病原体的携带。没有一种策略是完全有效的，益生菌往往无法在动物中定植。我们试图通过量化一组不同的细菌对牛细胞的附着来阐明细菌附着所需的基因。我们还从健康奶牛中分离出非致病性，并表明代表性分离株可以在共培养物中与致病性菌株竞争。我们建议对这些菌株及其附着因子进行集中研究，以便更好地为牲畜设计益生菌和疫苗提供信息。
