Table_1_Morphological and Molecular Characterization of a New Mycobacterium avium Subsp. paratuberculosis S-Type Strain Genotype in Goats.xlsx

Paratuberculosis is a chronic bacterial disease of global importance mainly in domestic and wild ruminants, caused by Mycobacterium avium subsp. paratuberculosis (MAP). In goats, paratuberculosis is mostly caused by the “C-type” (cattle) and in a few cases by the “S-type” (sheep) strain of MAP. In 2017, a caprine S-type III isolate with a new VNTR profile was identified in a Swiss alpine region. In 2018, new caprine isolates with the same novel VNTR profile originating from a farm of a close by neighboring valley were analyzed. Here we report on this MAP S-type III outbreak in a Swiss dairy goat farm in which we investigated the pathological changes, distribution and genotype of MAP tissue homogenates. Full necropsy and histological examination were undertaken on two female adult goats with a history of weight loss and intermitting diarrhea. Routine and special stains were applied to characterize the morphological changes. DNA was extracted from 33 different tissue samples and tested for MAP by qPCR targeting IS900 and F57. Subtyping was performed, using the variable number tandem repeats (VNTR) and mycobacterial interspersed repetitive units (MIRU) approach. The goats showed moderate to marked emaciation and displayed typical clinical features of paratuberculosis. A moderate granulomatous enteritis and regional lymphadenitis with a small to moderate number of acid-fast bacteria within macrophages was detected. MAP detection was mainly restricted to the gastrointestinal tract, mesenteric and hepatic lymph nodes. Subtyping the S-type isolates using a panel of eight established MIRU-VNTR loci identified a new genotype, INMV 218.

副结核病（Paratuberculosis）是一种具有全球公共卫生与畜牧养殖重要性的慢性细菌性疾病，主要感染家养及野生反刍动物，其病原体为鸟分枝杆菌副结核亚种（Mycobacterium avium subsp. paratuberculosis，MAP）。在山羊群体中，副结核病多由MAP的"C型（牛源型）"菌株引发，仅少数病例由"S型（羊源型）"菌株导致。2017年，研究人员在瑞士阿尔卑斯山区分离到一株携带新型可变数目串联重复序列（Variable Number Tandem Repeats，VNTR）分型图谱的山羊源S型III型分离株。2018年，研究人员对来自邻近山谷某养殖场、携带相同新型VNTR分型图谱的新一批山羊源分离株展开了分析。本研究报道了瑞士某奶山羊农场暴发的MAP S型III型疫情，期间我们对MAP组织匀浆的病理变化、分布特征及基因型进行了系统探究。

本研究对2头存在体重下降、间歇性腹泻病史的成年母山羊实施了全面剖检与组织病理学检查。通过常规染色与特殊染色技术，对受试动物的形态学病变进行了精准鉴定。从33份不同组织样本中提取基因组DNA，并采用靶向IS900与F57基因的实时荧光定量PCR（quantitative real-time PCR，qPCR）方法开展MAP检测。采用可变数目串联重复序列（VNTR）与分枝杆菌散在重复单位（Mycobacterial Interspersed Repetitive Units，MIRU）分型技术对菌株进行亚型鉴定。

病理学观察结果显示，受试山羊呈现中度至重度消瘦，并表现出副结核病典型临床症状。检测发现中度肉芽肿性肠炎与区域性淋巴结炎，巨噬细胞内可见数量不等的抗酸杆菌。MAP的组织分布主要局限于胃肠道、肠系膜淋巴结及肝淋巴结。通过包含8个已验证基因座的MIRU-VNTR分型面板对S型分离株进行亚型鉴定，最终确定了一种新型基因型INMV 218。