Laboratory of Molecular, Cellular, and Environmental Rickettsiology, Department of Veterinary Biosciences, College of Veterinary Medicine, Infectious Diseases Institute, The Ohio State Universitygrid.261331.4, Columbus, Ohio, USA.
Veterinary Clinical Sciences, The Ohio State Universitygrid.261331.4, Columbus, Ohio, USA.
J Clin Microbiol. 2022 Jul 20;60(7):e0025022. doi: 10.1128/jcm.00250-22. Epub 2022 Jun 13.
Potomac horse fever (PHF) is an acute and potentially fatal enterotyphlocolitis of horses with clinical signs that include anorexia, fever, diarrhea, and laminitis. Its incidence is increasing despite a commercially available vaccine. PHF is caused by Neorickettsia risticii, and the recently rediscovered and classified . PHF diagnosis is currently accomplished using serology or nested PCR. However, both methods cannot distinguish the two species that cause PHF. Further, the current real-time PCR test fails to detect Thus, in this study, two species-specific real-time PCR assays based on and a genus-specific real-time PCR assay based on 16S rRNA gene were developed. The real-time PCR tests differentiated from in the field samples for which infection with either species had been verified using multiple other molecular tests and culture isolation, and the 16S rRNA gene real-time PCR detected both species in the samples. These tests were applied to new field culture isolates from three Canadian provinces (Alberta, Quebec, Ontario) and Ohio as well as archival DNA samples from suspected PHF cases to estimate the prevalence of in different geographic regions. The results suggest that frequently causes PHF in horses in Alberta and Quebec. The development of these tests will allow rapid, sensitive, and specific diagnosis of horses presenting with clinical signs of PHF. These tests will also enable rapid and targeted treatment and help develop broad-spectrum vaccines for PHF.
波托马克河马热病（PHF）是一种急性且潜在致命的马肠伤寒结肠炎，其临床症状包括食欲不振、发热、腹泻和蹄叶炎。尽管有市售疫苗，但该病的发病率仍在上升。PHF 由 Neorickettsia risticii 引起，最近重新发现并分类。PHF 的诊断目前使用血清学或巢式 PCR 进行。然而，这两种方法都无法区分引起 PHF 的两种立克次体。此外，目前的实时 PCR 检测无法检测到。因此，在这项研究中，基于 和一种基于 16S rRNA 基因的属特异性实时 PCR 开发了两种 种特异性实时 PCR 检测方法。实时 PCR 检测方法在野外样本中区分了 和 ，这些样本的感染已经通过多种其他分子检测和培养分离得到证实，16S rRNA 基因实时 PCR 检测到了样本中的两种 。这些检测方法应用于来自加拿大三个省（艾伯塔省、魁北克省、安大略省）和俄亥俄州的新的野外培养分离株以及疑似 PHF 病例的档案 DNA 样本，以估计不同地理区域中 的流行率。结果表明， 在艾伯塔省和魁北克省的马中经常引起 PHF。这些检测方法的开发将允许快速、敏感和特异性诊断出现 PHF 临床症状的马。这些检测方法还将能够快速和有针对性地治疗，并有助于开发针对 PHF 的广谱疫苗。
