Mycoplasma hyopneumoniae, the primary pathogenic bacterium causing enzootic pneumonia, significantly affects worldwide swine production. The infection is usually persistent and bacterial identification and isolation of M. hyopneumoniae in clinical samples are challenging due to the fastidious requirements for its growth. Hence, new practical surveillance tools that improve or complement existing diagnostics on M. hyopneumoniae are desirable, especially in early infection. The objective of this study was to identify potential metabolite markers of early M. hyopneumoniae infection in pigs through metabolomics analysis. Samples obtained from pigs in a previous M. hyopneumoniae experimental infection were used in this study. Briefly, two pigs served as mock inoculated controls and ten pigs were intra-tracheally inoculated with M. hyopneumoniae. Sera, laryngeal swabs (LS), and tracheo-bronchial lavage fluid (TBLF) were collected from all pigs at 0, 2, 5, 9, 14, 21 and 28 days post-inoculation (dpi). Bronchial swabs (BS) were collected post-mortem at 28 dpi. Mycoplasma hyopneumoniae infection was confirmed by PCR in LS, TBLF and BS. Serum metabolites were profiled using high-resolution liquid chromatography–mass spectrometry (LC–MS) analysis. Metabolite markers were identified by structural analysis following multivariate analysis of LC–MS data. The results showed that M. hyopneumoniae infection time-dependently altered the serum levels of selective amino acids and fatty acids. α-Aminobutyric acid and long-chain fatty acids were markedly increased at 14 and 21 dpi in inoculated pigs (p < 0.05). These results indicated that M. hyopneumoniae infection caused systemic changes in host metabolism, warranting further studies to determine underlying biochemical and physiological mechanisms responsible for the observed changes.

中文翻译：

---

猪早期猪肺炎支原体感染的血清代谢物标志物

猪肺炎支原体是引起犬瘟性肺炎的主要致病菌，对全世界的猪生产都有重大影响。感染通常是持续性的，并且由于其生长的严格要求，细菌鉴定和临床样品中猪肺炎支原体的分离是具有挑战性的。因此，需要新的实用的监测工具来改善或补充猪肺炎支原体的现有诊断，尤其是在早期感染中。这项研究的目的是通过代谢组学分析来确定猪早期猪肺炎支原体感染的潜在代谢物标志物。在这项研究中使用了先前猪肺炎支原体实验感染中从猪身上获得的样本。简而言之，将两只猪用作模拟接种的对照，并对十只猪进行气管内接种猪肺炎支原体。世罗 在接种后第0、2、5、9、14、21和28天（dpi）从所有猪中收集喉拭子（LS）和气管支气管灌洗液（TBLF）。死后以28 dpi收集支气管拭子（BS）。通过PCR在LS，TBLF和BS中证实了猪肺炎支原体感染。使用高分辨率液相色谱-质谱（LC-MS）分析对血清代谢产物进行分析。通过对LC-MS数据进行多变量分析后，通过结构分析来鉴定代谢物标记物。结果表明猪肺炎支原体感染随时间改变了血清中选择性氨基酸和脂肪酸的水平。接种猪在14和21 dpi时，α-氨基丁酸和长链脂肪酸显着增加（p <0.05）。这些结果表明猪肺炎支原体感染导致宿主代谢系统性改变，