Newcastle disease in avian species is caused by Newcastle disease virus (NDV). It is responsible for large economic losses to the poultry industry. The early diagnosis of NDV infection is important for epidemiologic control and clinical management. The present study aimed to develop reverse transcription polymerase spiral reaction (RT-PSR) assay that accurately detects the NDV at isothermal temperature. The RT-PSR assay was developed using specifically designed primers targeting the conserved fusion gene of NDV. The assay could be performed within 2 h at an isothermal temperature of 65 °C. The developed assay is highly sensitive and capable to detect as low as 1.08 fg of template. It was found to be 1000-fold more sensitive than conventional RT-PCR and was comparable to real-time RT-PCR assay. The developed assay was found to be specific as it did not detect closely related infectious bronchitis virus and Merck disease virus. Further, the developed assay was evaluated with clinical samples and it has shown > 99% concordance with RT-PCR methods. To the best of our knowledge this is the first report of isothermal detection of NDV without the need of high-end equipment like thermal cycler. Moreover, this assay has the potential to detect NDV under field conditions. In conclusions, the results of this study indicated that the RT-PSR assay is a simple, rapid, sensitive, and specific assay for the detection of NDV that may improve diagnostic potential in clinical laboratories or can be used at diagnostic laboratories with the least infrastructure or even at field condition.

禽类新城疫是由新城疫病毒（NDV）引起的。它给家禽业造成了巨大的经济损失。新城疫病毒感染的早期诊断对于流行病学控制和临床治疗具有重要意义。本研究旨在开发逆转录聚合酶螺旋反应（RT-PSR）测定法，在等温温度下准确检测新城疫病毒。 RT-PSR 检测是使用专门设计的针对 NDV 保守融合基因的引物开发的。该测定可在 65 °C 等温温度下 2 小时内完成。开发的检测方法灵敏度高，能够检测低至 1.08 fg 的模板。结果发现，它的灵敏度比传统 RT-PCR 灵敏 1000 倍，并且与实时 RT-PCR 检测相当。所开发的检测方法具有特异性，因为它没有检测到密切相关的传染性支气管炎病毒和默克病病毒。此外，利用临床样本对所开发的检测方法进行了评估，结果显示与 RT-PCR 方法的一致性 > 99%。据我们所知，这是第一份无需热循环仪等高端设备即可等温检测新城疫病毒的报告。此外，该测定法具有在现场条件下检测 NDV 的潜力。总之，本研究结果表明，RT-PSR 检测是一种简单、快速、灵敏且特异的 NDV 检测方法，可提高临床实验室的诊断潜力，或可用于基础设施最少的诊断实验室。甚至在现场条件下。