Bovine tuberculosis (bTB) is a chronic disease of cattle caused by Mycobacterium bovis. During early-stage infection, M. bovis-infected cattle shed mycobacteria through nasal secretions, which can be detected via nested-polymerase chain reaction (PCR) experiments. Little research has focused on immune responses in nested PCR-positive (bTB PCR-P) or nested PCR-negative (bTB PCR-N) M. bovis-infected cattle. Here, we investigated the transcriptomes of peripheral blood mononuclear cells (PBMCs), with or without stimulation by purified protein derivative of bovine tuberculin (PPD-B), among bTB PCR-P, bTB PCR-N, and healthy cattle using RNA-Seq. We also explored the potential value of PBMC transcripts as novel biomarkers for diagnosing bTB. Numerous differentially expressed genes were identified following pair-wise comparison of different groups, with or without PPD-B stimulation (adjusted p < 0.05). Compared with healthy cattle, bTB PCR-P, and bTB PCR-N cattle shared 5 significantly dysregulated biological pathways, including Cytokine-cytokine receptor interaction, NF-kappa B signaling pathway, Hematopoietic cell lineage, Osteoclast differentiation and HTLV-I infection. Notably, dysregulated biological pathways of bTB PCR-P and bTB PCR-N cattle were associated with cell death and phagocytosis, respectively. Lymphotoxin alpha and interleukin-8 could potentially differentiate M. bovis-infected and healthy cattle upon stimulation with PPD-B, with area-under-the-curve (AUC) values of 0.9991 and 0.9343, respectively. B cell lymphoma 2 and chitinase 3-like 1 might enable differentiation between bTB PCR-P and bTB PCR-N upon stimulation with PPD-B, with AUC values of 0.9100 and 0.8893, respectively. Thus, the PBMC transcriptome revealed the immune responses in M. bovis-infected cattle (bTB PCR-P and bTB PCR-N) and may provide a novel sight in bTB diagnosis.

中文翻译：

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牛结核病牛外周血单个核细胞转录组的潜在诊断价值。

牛结核病（bTB）是牛分枝杆菌引起的一种慢性疾病。在早期感染期间，感染牛分枝杆菌的牛通过鼻腔分泌物分泌分枝杆菌，可以通过巢式聚合酶链反应（PCR）实验检测到。很少有研究集中在嵌套PCR阳性（bTB PCR-P）或嵌套PCR阴性（bTB PCR-N）牛分枝杆菌感染牛的免疫应答。在这里，我们研究了使用或不使用牛结核菌素纯化蛋白衍生物（PPD-B）刺激的外周血单个核细胞（PBMC）的转录组，使用RNA-Seq在bTB PCR-P，bTB PCR-N和健康牛中。我们还探讨了PBMC转录本作为诊断bTB的新型生物标志物的潜在价值。在对不同组进行成对比较后，鉴定出许多差异表达基因，有无PPD-B刺激（调整后的p <0.05）。与健康牛相比，bTB PCR-P和bTB PCR-N牛共有5条明显失调的生物学通路，包括细胞因子-细胞因子受体相互作用，NF-κB信号通路，造血细胞谱系，破骨细胞分化和HTLV-1感染。值得注意的是，bTB PCR-P和bTB PCR-N牛的生物通路失调分别与细胞死亡和吞噬作用有关。在PPD-B刺激下，Lymphotoxinα和IL-8可能会区分牛分枝杆菌感染的牛和健康的牛，曲线下面积（AUC）值分别为0.9991和0.9343。B细胞淋巴瘤2和几丁质酶3样1可能会在PPD-B刺激下使bTB PCR-P和bTB PCR-N区分，AUC值为0.9100和0.8893，分别。因此，PBMC转录组揭示了牛分枝杆菌感染牛的免疫应答（bTB PCR-P和bTB PCR-N），可能为bTB诊断提供新的视野。