Arsenault Julie, Singh Sohal Jagdip, Leboeuf Anne, Hélie Pierre, Fecteau Gilles, Robinson Yves, L'Homme Yvan
Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada (Arsenault, Hélie, Fecteau).
Canadian Food Inspection Agency, Saint-Hyacinthe, Quebec, Canada (Sohal, Robinson, L'Homme).
J Vet Diagn Invest. 2019 Jan;31(1):58-68. doi: 10.1177/1040638718810744. Epub 2018 Nov 2.
Paratuberculosis is a chronic infectious enteritis of ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP). In sheep, the antemortem detection of the infection is challenging given the slow progression of the disease and the lack of sensitive, specific, and cost-effective validated tests. We adapted an in-house real-time PCR (rtPCR) assay targeting the multi-copy IS 900 element of MAP. The sensitivity and specificity of this essay for the detection of MAP infection were estimated in a convenience sample of culled ewes from 7 infected flocks and compared to a commercial fecal rtPCR, a commercial ELISA, and fecal culture. An infected ewe was defined as a ewe with a positive culture of the ileum and/or mesenteric lymph node. A non-infected ewe was defined as a ewe negative in intestinal tissue culture, negative in fecal culture, and with no lesions consistent with paratuberculosis. The in-house rtPCR had a sensitivity estimate of 84% (95% confidence interval [CI]: 59%, 97%) among the 44 infected ewes, which was significantly higher ( p ⩽ 0.05) than the sensitivity of a commercial fecal rtPCR (52%, 95% CI: 27%, 76%; or 63%, 95% CI: 35%, 87% depending on the cutoff used), an ELISA (14%, 95% CI:2.0%, 41%), and fecal culture (21%, 95% CI: 2.7%, 59%). No statistical difference in assay specificities was observed for the 30 non-infected ewes. The in-house rtPCR is a promising tool that could be used advantageously for the antemortem detection of MAP infection in sheep.
副结核病是由鸟分枝杆菌副结核亚种（MAP）引起的反刍动物慢性传染性肠炎。在绵羊中，鉴于该病进展缓慢且缺乏灵敏、特异且经济有效的经过验证的检测方法，生前感染检测具有挑战性。我们采用了一种针对MAP多拷贝IS 900元件的内部实时荧光定量聚合酶链反应（rtPCR）检测方法。在来自7个感染羊群的淘汰母羊便利样本中估计了该检测方法检测MAP感染的敏感性和特异性，并与一种商业粪便rtPCR、一种商业酶联免疫吸附测定（ELISA）和粪便培养进行比较。感染母羊定义为回肠和/或肠系膜淋巴结培养阳性的母羊。未感染母羊定义为肠道组织培养阴性、粪便培养阴性且无符合副结核病病变的母羊。在44只感染母羊中，内部rtPCR的敏感性估计为84%（95%置信区间[CI]：59%，97%），显著高于（p⩽0.05）一种商业粪便rtPCR的敏感性（52%，95%CI：27%，76%；或根据所用临界值为63%，95%CI：35%，87%）、ELISA的敏感性（14%，95%CI：2.0%，41%）和粪便培养的敏感性（21%，95%CI：2.7%，59%）。对于30只未感染母羊，未观察到检测特异性的统计学差异。内部rtPCR是一种有前景的工具，可有利地用于绵羊MAP感染的生前检测。
