Infectious Bursal Disease Virus: Molecular Epidemiologic Perspectives and Impact on Vaccine Efficacy Against Avian Influenza and Newcastle Disease Viruses
Infectious Bursal Disease Virus: Molecular Epidemiologic Perspectives and Impact on Vaccine Efficacy Against Avian Influenza and Newcastle Disease Viruses
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DOI：
10.1637/aviandiseases-d-19-00086
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发表时间：
2019-12-01
期刊：
影响因子：
1.4
通讯作者：
Eid, Amal A. M.
中科院分区：
文献类型：
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作者：
El-Aried, Tamer A.;Mansour, Shimaa M. G.;Eid, Amal A. M.
传染性法氏囊病（IBD）病毒（IBDV）是鸡的一种高度传染性和免疫抑制疾病的病原体，尽管广泛接种疫苗，但仍给家禽业造成巨大的经济损失。对从接种疫苗的禽类中分离出的IBDV野毒株进行分析，将大大改善目前的免疫方案，并支持开发提供更好免疫力的疫苗。本研究研究了商品肉鸡养殖场IBDV的遗传特征和病理特征，以及IBDV感染对野战条件下接种禽流感病毒（AIV）和新城疫病毒（NDV）效果的影响。初步诊断IBD是根据禽群的历史和特征性的大体病理结果。镜下，法氏囊滤泡淋巴细胞减少，单核淋巴细胞浸润，囊性空泡反映了IBDV感染。经分子分析，检测鸡群感染IBDV（57.1%）。对14株埃及IBDVs的VP2高变区进行系统发育分析发现，大多数病毒（n = 12）聚集在基因组3内，而2株病毒与基因组1的减毒疫苗分离株密切相关。氨基酸（aa）序列分析表明，大多数菌株在VP2蛋白上具有5个一致的位点（222A、242I、256I、294I和299S），这是极毒IBDV （vvIBDV）的特征。血清学结果显示IBDV具有免疫抑制作用，低致病性AIV亚型H9N2和NDV的血凝抑制效价分别降低1.6 ~ 2.6和1.4 ~ 2.6，平均对数(2)。检测的IBDVs在VP2肽的高变域内显示出高突变率。结果突出表明，有必要对埃及鸡群中的IBDV感染进行全面监测。
Infectious bursal disease (IBD) virus (IBDV) is the causative agent of a highly contagious and immunosuppressive disease of chickens with huge economic losses to the poultry industry despite extensive vaccination. Analysis of isolated IBDV field strains from vaccinated birds would greatly improve the current immunization regimens and support the development of vaccines that offer better immunity. The study investigated the genetic characteristics and pathologic features of IBDVs in commercial broiler chicken farms, as well as the effect of IBDV infection on the efficacy of vaccination against avian influenza virus (AIV) and Newcastle disease virus (NDV) under field conditions. A preliminary diagnosis of IBD was made on the basis of the flock history and the characteristic gross pathologic findings. Microscopically, lymphoid depletion in bursal follicles with infiltration of lymphomononuclear cells along with cystic cavitations reflected the IBDV infection. The molecular analysis confirmed the IBDV infection in (57.1%) of tested flocks. Upon phylogenetic analysis of the VP2 hypervariable region of 14 Egyptian IBDVs, most viruses (n = 12) were clustered within the genogroup 3, while two viruses were closely related to attenuated vaccine isolates in genogroup 1. The analysis of the amino acid (aa) sequences revealed that most of the strains possessed five consistent aas at the VP2 protein (222A, 242I, 256I, 294I, and 299S), which are characteristic for the very virulent IBDV (vvIBDV). Serology indicated the immunosuppressive effect of IBDV, which is represented by a decrease (1.6-2.6 and 1.4-2.6 mean log(2)) in the hemagglutination inhibition titer of the low pathogenic AIV subtype H9N2 and NDV, respectively. The examined IBDVs showed a high mutation rate within the hypervariable domain of the VP2 peptide. The results highlighted the need for carrying out an inclusive surveillance of IBDV infections in chicken flocks in Egypt.