Institute of Animal Health, Fayoum, 63511, Egypt.
Department of Poultry Disease, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef, 62511, Egypt.
Trop Anim Health Prod. 2022 Aug 1;54(4):243. doi: 10.1007/s11250-022-03234-3.
Newcastle disease (ND) is one of the most important poultry diseases worldwide and can lead to annual losses of up to 80% of backyard chickens in Africa. A retrospective cohort of 6 years was planned to screen the NDV in intensive chicken and turkey flocks. The existence of velogenic NDV strain was screened in different poultry flocks showing suspected signs of NDV using real-time RT-PCR targeting the F gene of the velogenic strain. A total of 843 poultry flocks were screened during the cohort. Samples were classified based on the month and year as well as the poultry type. All flocks should be negative for avian influenza virus as an inclusion criterion of the study. The F gene of a randomly selected positive sample from each year as well as an archival sample from 2005 was sequenced. An overall of 52.4% (443/842) of the tested farms showed positive results for the velogenic NDV. The cumulative percentage of positive flocks to the total positive flocks per month ranged from 5.9 to 11.8%. The results revealed that NDV is circulating across all months annually without evidence of seasonal tendency of the disease. Most of the strains belong to genotype VII.1.1, with only two strains related to XXI.1.1 and XXI.2. All VII.1.1 strains possess arginine at 27 position while XXI.1.1 and XXI.2 strains showed cysteine at 27 and amino acid substitutions in the signal peptide, cleavage site, and neutralizing epitopes. In conclusion, the current molecular epidemiological surveillance confirms the enzootic nature of NDV. It circulates all year round with no evidence of seasonal incidence. Genotype VII is the most predominant NDV genotype in Egypt.
新城疫（ND）是全球最重要的家禽疾病之一，可导致非洲后院鸡的年损失高达 80%。本研究计划对密集型鸡和火鸡群进行为期 6 年的回顾性队列研究，以筛选新城疫病毒（NDV）。使用针对速发型 NDV 株 F 基因的实时 RT-PCR 筛选出具有速发型 NDV 株的不同家禽群中的存在。在该队列期间共筛选了 843 个家禽群。根据月份和年份以及家禽类型对样本进行分类。所有禽群都应为禽流感病毒阴性，这是本研究的纳入标准。每年从每个随机选择的阳性样本以及 2005 年的存档样本中随机选择一个 F 基因进行测序。总共 52.4%（443/842）的检测农场对速发型 NDV 呈阳性结果。每月阳性禽群的累积百分比占阳性禽群的百分比为 5.9%至 11.8%。结果表明，NDV 全年在所有月份传播，没有疾病季节性倾向的证据。大多数毒株属于基因型 VII.1.1，只有两株与 XXI.1.1 和 XXI.2 相关。所有 VII.1.1 株在 27 位都含有精氨酸，而 XXI.1.1 和 XXI.2 株在 27 位含有半胱氨酸，并且在信号肽、切割位点和中和表位中存在氨基酸取代。总之，目前的分子流行病学监测证实了 NDV 的地方病性质。它全年传播，没有季节性发病的证据。基因型 VII 是埃及最主要的 NDV 基因型。
