Alemu Esubalew Endale, Senbata Bayeta, Sombo Melaku, Guyassa Chala, Alemayehu Dawit Hailu, Kidane Eleni, Mihret Adane, Mulu Andargachew, Dinka Hunduma
Department of Applied Biology, Adama Science and Technology University, Adama, Ethiopia.
Molecular Biology Laboratory, Animal Health Institute (AHI), Sebeta, Ethiopia.
Vet Med (Auckl). 2024 May 8;15:149-157. doi: 10.2147/VMRR.S442787. eCollection 2024.
Newcastle disease (ND) is a highly infectious poultry disease that causes major economic losses worldwide. The disease is caused by Newcastle Disease Virus (NDV) and early detection and identification of the viral strain is essential. Having knowledge of the NDV strain genotype that circulates in some regions would help in designing an effective vaccine to control the disease. In this regard, there is little information on NDV strain in chickens in mid Rift Valley and the central part of Ethiopia. Therefore, the purpose of this study was to detect and characterize NDV strain genotype from chickens in mid-Rift Valley and the central part of Ethiopia and test whether this NDV strain genotype matches the vaccine strain currently used in the study area.
A total of 98 samples: 78 (tracheal and cloacal) swabs from chicken pools of five and 20 tissue samples were collected. To detect NDV strain, conserved region of the virus Matrix (M) gene was amplified by qRT-PCR. To characterize NDV strain genotypes, M-gene positive samples were specifically re-amplified by conventional PCR targeting the Fusion (F) gene region and sequenced by Sanger method.
13.26% of tested samples were positive for NDV strain in the study area with statistically significant difference (P<0.05) among the study sites. Further characterization of the F genes from NDV strain isolates by phylogenetic analysis indicated that one field isolate clustered with genotype VII whereas three of the isolates clustered to genotype I, II, and III. The isolate of the current NDV strain vaccine in use in the study area clustered with genotype II.
The current study indicates the existence of different NDV strain genotype from that of the vaccine strain currently used. Even though large-scale characterization of several isolates is required at national level, the current study laid baseline information for the existence of variations between field NDV strain genotype and vaccine strain currently used against ND in the country.
新城疫（ND）是一种高度传染性的家禽疾病，在全球范围内造成重大经济损失。该疾病由新城疫病毒（NDV）引起，早期检测和鉴定病毒株至关重要。了解在某些地区传播的NDV株基因型将有助于设计有效的疫苗来控制该疾病。在这方面，关于埃塞俄比亚中裂谷和中部地区鸡群中NDV株的信息很少。因此，本研究的目的是检测和鉴定埃塞俄比亚中裂谷和中部地区鸡群中的NDV株基因型，并测试该NDV株基因型是否与研究区域目前使用的疫苗株匹配。
共收集了98份样本：来自5个鸡群的78份（气管和泄殖腔）拭子以及20份组织样本。为了检测NDV株，通过qRT-PCR扩增病毒基质（M）基因的保守区域。为了鉴定NDV株基因型，对M基因阳性样本通过靶向融合（F）基因区域的常规PCR进行特异性重新扩增，并采用桑格法进行测序。
研究区域中13.26%的检测样本对NDV株呈阳性，各研究地点之间存在统计学显著差异（P<0.05）。通过系统发育分析对NDV株分离物的F基因进行进一步鉴定表明，一株田间分离物与基因型VII聚类，而三株分离物分别聚类到基因型I、II和III。研究区域目前使用的NDV株疫苗分离物与基因型II聚类。
当前研究表明存在与目前使用的疫苗株不同的NDV株基因型。尽管在国家层面需要对多个分离物进行大规模鉴定，但当前研究为该国田间NDV株基因型与目前用于预防新城疫的疫苗株之间存在差异提供了基线信息。
