Exopol. Veterinary Diagnostic and Autogenous Vaccine Laboratory, Polígono Río Gállego, D/8. 50840 San Mateo de Gállego, Zaragoza, Spain.
Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain; Centro de Vigilancia Sanitaria Veterinaria (VISAVET), Universidad Complutense, Madrid, Spain.
Vet Microbiol. 2021 Jul;258:109121. doi: 10.1016/j.vetmic.2021.109121. Epub 2021 May 15.
This study compares the utility of a commercially available multiplex q-PCR assay for serotyping A1, A2, and A6 M. haemolytica serotypes with indirect hemagglutination, for determining the relative distribution of M. haemolytica capsular types associated with respiratory disorders in cattle, sheep, and goats. For the 129 isolates analyzed, both q-PCR and IHA assays exhibited nearly complete agreement for capsular types A1 (k = 0.965) and A2 (k = 0.888) and substantial agreement for A6 (k = 0.801). Despite the overall good performance of the commercial q-PCR, its effectiveness differed between the host origin of the isolates. The serotype was identified by q-PCR in 83.3 % of cattle, 77.8 % of goat, and 53.8 % of sheep isolates. Combining the results of both methods, A1 was the most prevalent in cattle and sheep (55.6 % and 22.25 %, respectively) but was not detected in goats, A2 was the most prevalent in goats (61.1 %) and the second most prevalent in cattle (16.7 %) and sheep (20.5 %). The prevalence of A6 was 7.4 %, 5.1 %, and 16.7 % in cattle, sheep, and goats, respectively. Other capsular types determined exclusively by IHA were A16 in cattle, A9 in goats, and A7, A8, A9, and A13 in sheep. Capsular type diversity was greater in sheep (H = 0.601) than in cattle (H = 0.408) and goat (H = 0.330) isolates. The commercial multiplex q-PCR is a valuable tool, alternative to IHA, for identifying isolates of capsular types A1, A2, and A6, the most frequent serotypes of M. haemolytica associated with respiratory disease in ruminants. However, when testing sheep isolates it should be complemented with immunological assays due to the wider range of serotypes implicated.
本研究比较了一种商用多重 q-PCR 检测试剂盒用于 A1、A2 和 A6 型 M. haemolytica 血清型的血清分型，与间接血凝试验（IHA）相比，该方法用于确定与反刍动物呼吸道疾病相关的 M. haemolytica 荚膜型的相对分布。在分析的 129 株分离株中，q-PCR 和 IHA 检测试剂盒对荚膜型 A1（k=0.965）和 A2（k=0.888）的检测结果几乎完全一致，对 A6（k=0.801）的检测结果具有高度一致性。尽管商用 q-PCR 的整体性能良好，但它的有效性在分离株的宿主来源上存在差异。q-PCR 可识别 83.3%的牛、77.8%的山羊和 53.8%的绵羊分离株的血清型。结合两种方法的结果，A1 是牛和绵羊中最常见的血清型（分别为 55.6%和 22.25%），但在山羊中未检测到，A2 是山羊中最常见的血清型（61.1%），在牛和绵羊中分别是第二常见的血清型（16.7%和 20.5%）。A6 在牛、绵羊和山羊中的流行率分别为 7.4%、5.1%和 16.7%。仅通过 IHA 确定的其他荚膜型包括牛中的 A16、山羊中的 A9 以及绵羊中的 A7、A8、A9 和 A13。绵羊分离株的荚膜型多样性（H=0.601）高于牛（H=0.408）和山羊（H=0.330）分离株。该商用多重 q-PCR 是一种有价值的工具，可替代 IHA 用于鉴定与反刍动物呼吸道疾病相关的最常见 M. haemolytica 血清型 A1、A2 和 A6 的分离株。然而，在测试绵羊分离株时，由于涉及的血清型范围更广，因此应补充免疫检测方法。
