Department of Veterinary Pathology, Faculty of Veterinary Medicine, University of Ilorin, Ilorin, Nigeria.
Regional Laboratory for Animal Influenzas and Transboundary Animal Diseases, Virology Division, National Veterinary Research Institute, Vom, Nigeria.
Avian Pathol. 2020 Aug;49(4):394-403. doi: 10.1080/03079457.2020.1757035. Epub 2020 Jun 11.
Newcastle disease (ND) is an infectious viral poultry disease with great economic consequences. In developing countries, outbreaks of ND caused by virulent Newcastle disease virus (NDV) have been identified as a limiting factor to the growth of the poultry industry. Limited reports exist on the pathology of natural field infection caused by NDV genotype XVII in chickens. Here, we present clinical, pathological and molecular investigation of confirmed ND in a 24-week-old layer-type, semi-intensive poultry flock with recorded mortality of over 50%. During PM examination, tissues were harvested for virus isolation, histopathology and immunohistochemistry. Virus isolation was performed in 10-day-old embryonated chicken eggs, and a haemagglutinating agent thereof identified by one-step reverse transcription-polymerase chain reaction (RT-PCR). For the genotyping of the isolate, the full fusion gene was sequenced. Clinical signs observed included general body lethargy, inappetence and greenish diarrhoeic faeces from the cloaca before death with daily mortality exceeding 100 chickens. The pathology was characteristic of a viral haemorrhagic infection, with serosal haemorrhages, mucosal surface erosion and ulceration. In most of the carcasses, the main lesions seen included airsacculitis, meningeal congestion, haemorrhagic oophoritis, pancreatic necrosis, enteritis and faecal matting of the vent. Virus isolation and RT-PCR made a confirmatory diagnosis of ND. Based on the cleavage site motif sequence (RRQKR/F), the isolate was identified as a virulent strain with phylogenetic analysis showing clustering in genotype XVII viruses. To the best of the authors' knowledge, this is the first report describing the pathological findings of a natural outbreak caused by NDV involving viruses of genotype XVII. First report of a natural outbreak of Newcastle disease in White Yarkon Leghorns. The outbreak was caused by virulent NDV belonging to genotype XVII. Pathology differed slightly from those in experimental studies using SPF and other unvaccinated chickens.
新城疫（ND）是一种具有重大经济后果的传染性病毒性家禽病。在发展中国家，由强毒新城疫病毒（NDV）引起的 ND 爆发已被确定为家禽业发展的限制因素。关于 NDV 基因型 XVII 引起的自然田间感染的病理学报道有限。在这里，我们报告了一个 24 周龄层式半密集型家禽群中确认的 ND 的临床、病理和分子调查，该家禽群的死亡率记录超过 50%。在 PM 检查期间，采集组织进行病毒分离、组织病理学和免疫组织化学检查。病毒分离在 10 日龄鸡胚中进行，并用一步 RT-PCR 鉴定其血凝剂。为了对分离株进行基因分型，对全长融合基因进行了测序。观察到的临床症状包括全身乏力、食欲不振和从死亡前的泄殖腔排出绿色水样粪便，每日死亡率超过 100 只鸡。病理学特征为病毒性出血性感染，伴有浆膜出血、黏膜表面侵蚀和溃疡。在大多数尸体中，主要病变包括气囊炎、脑膜充血、出血性卵黄性腹膜炎、胰腺坏死、肠炎和泄殖腔粪便粘连。病毒分离和 RT-PCR 做出了 ND 的确诊诊断。基于裂解位点基序序列（RRQKR/F），分离株被鉴定为具有强毒力的毒株，系统发育分析显示其聚类在基因型 XVII 病毒中。据作者所知，这是首次描述涉及基因型 XVII 病毒的自然爆发引起的 ND 的病理发现。怀特亚尔科恩莱格霍恩鸡新城疫的首次自然爆发报告。此次爆发是由强毒 NDV 引起的，属于基因型 XVII。病理学与使用 SPF 和其他未接种疫苗的鸡进行的实验研究略有不同。
