Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada.
Lethbridge Research Centre, Agriculture and Agri-Food Canada, Lethbridge, AB, Canada.
Front Cell Infect Microbiol. 2021 Mar 17;11:633573. doi: 10.3389/fcimb.2021.633573. eCollection 2021.
Shiga toxin (Stx) is the main virulence factor of Shiga toxin-producing (STEC), and ruminants are the main reservoir of STEC. This study assessed the abundance and expression of genes and the expression of host immune genes, aiming to determine factors affecting these measures and potential gene markers to differentiate gene expression in the recto-anal junction of feedlot beef cattle. Rectal tissue and content samples were collected from 143 feedlot steers of three breeds (Angus, Charolais, and Kinsella Composite) over 2 consecutive years 2014 (n=71) and 2015 (n=72). The abundance and expression of and were quantified using qPCR and reverse-transcription-qPCR (RT-qPCR), respectively. Four immune genes (, and ), previously reported to be down-regulated in super-shedder cattle (i.e., > 10 CFU g) were selected, and their expression was evaluated using RT-qPCR. The gene abundance was only detected in tissue samples collected in year 2 and did not differ among breeds. The gene was detected in STEC from all samples collected in both years and did not vary among breeds. The abundance of and differed (P < 0.001) in content samples collected across breeds (:AN>CH>KC, : AN=CH>KC) in year 1, but not in year 2. Expression of was detected in 13 RAJ tissue samples (2014: n=6, 2015: n=7), while expression of was not detected. Correlation analysis showed that the expression of was negatively correlated with the expression of (R=-0.56, P=0.05) and positively correlated with the expression of (R=0.60, P=0.05). The random forest model and Boruta method revealed that expression of selected immune genes could be predictive indicators of expression with prediction accuracy of > > >. Our results indicate that the abundance of could be affected by cattle breed and sampling year, suggesting that host genetics and environment may influence STEC colonization of the recto-anal junction of feedlot cattle. Additionally, the identified relationship between expressions of host immune genes and suggests that the host animal may regulate expression in colonizing STEC through immune functions.
志贺毒素（Stx）是产志贺毒素大肠杆菌（STEC）的主要毒力因子，反刍动物是 STEC 的主要储存宿主。本研究评估了基因的丰度和表达以及宿主免疫基因的表达，旨在确定影响这些措施的因素和潜在的基因标记，以区分育肥牛直肠-肛门交界处的基因表达。在连续两年（2014 年，n=71；2015 年，n=72），从三个品种（安格斯牛、夏洛莱牛和金赛拉复合牛）的 143 头育肥牛中收集直肠组织和内容物样本。使用 qPCR 和逆转录 qPCR（RT-qPCR）分别定量和的丰度和表达。选择了四个先前报道在超级脱落者牛（即>10 CFU g）中下调的免疫基因（、和），并使用 RT-qPCR 评估其表达。仅在 2 年采集的组织样本中检测到基因丰度，且品种间无差异。在两年中采集的所有样本中均检测到 STEC，且品种间无差异。和在内容物样本中的丰度在品种间存在差异（P < 0.001）（：AN>CH>KC，：AN=CH>KC），但在 2 年中没有差异。在 13 个 RAJ 组织样本中检测到的表达（2014 年：n=6，2015 年：n=7），但未检测到的表达。相关性分析表明，与的表达呈负相关（R=-0.56，P=0.05），与的表达呈正相关（R=0.60，P=0.05）。随机森林模型和 Boruta 方法表明，所选免疫基因的表达可以作为预测的指标，预测准确性> > >。我们的结果表明，的丰度可能受到牛品种和采样年份的影响，这表明宿主遗传和环境可能影响育肥牛直肠-肛门交界处的 STEC 定植。此外，鉴定的宿主免疫基因与的表达之间的关系表明，宿主动物可能通过免疫功能调节定植 STEC 中的表达。
