A molecular epidemiology study based on VP2 gene sequences reveals that a new genotype of infectious bursal disease virus is dominantly prevalent in Italy
A molecular epidemiology study based on VP2 gene sequences reveals that a new genotype of infectious bursal disease virus is dominantly prevalent in Italy
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DOI：
10.1080/03079457.2016.1165792
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发表时间：
2016-01-01
期刊：
影响因子：
2.8
通讯作者：
Catelli, Elena
中科院分区：
文献类型：
--
作者：
Lupini, Caterina;Giovanardi, Davide;Catelli, Elena
在没有IBD临床症状的意大利IBD活疫苗接种肉鸡中检测到一种独特的IBD病毒基因型(ITA)。系统发育分析表明，ITA毒株与GenBank检索到的IBDV经典毒株或超强毒株以及疫苗毒株的同源参考序列不同。新的基因在VP2高变区的关键位置表现出特殊的分子特征，影响带电的或潜在的糖基化氨基酸，实际上与病毒性质的重要变化有关。2013至2014年间在意大利检测到的41个IBDV毒株的特征表明，ITA在意大利家禽人口稠密的地区出现，占两年期间常规诊断活动期间IBDV检测的68%，尽管大规模接种疫苗诱导了免疫。还检测到4株超强毒株(DV86)和1株经典株(HPR2)，以及8株疫苗株。目前可用的流行病学和临床数据不允许定义ITA基因的致病程度。只有在安全的隔离条件下进行体内实验性致病性研究，通过对临床症状和宏观/微观损伤的评估，才能最终澄清新的意大利基因型的毒力。
A distinctive infectious bursal disease (IBD) virus genotype (ITA) was detected in IBD-live vaccinated broilers in Italy without clinical signs of IBD. It was isolated in specific-pathogen-free eggs and molecularly characterized in the hypervariable region of the virus protein (VP) 2. Phylogenetic analysis showed that ITA strains clustered separately from other homologous reference sequences of IBDVs, either classical or very virulent, retrieved from GenBank or previously reported in Italy, and from vaccine strains. The new genotype shows peculiar molecular characteristics in key positions of the VP2 hypervariable region, which affect charged or potentially glycosylated amino acids virtually associated with important changes in virus properties. Characterization of 41 IBDV strains detected in Italy between 2013 and 2014 showed that ITA is emergent in densely populated poultry areas of Italy, being 68% of the IBDV detections made during routine diagnostic activity over a two-year period, in spite of the immunity induced by large-scale vaccination. Four very virulent strains (DV86) and one classical strain (HPR2), together with eight vaccine strains, were also detected. The currently available epidemiological and clinical data do not allow the degree of pathogenicity of the ITA genotype to be defined. Only in vivo experimental pathogenicity studies conducted in secure isolation conditions, through the evaluation of clinical signs and macro/microscopic lesions, will clarify conclusively the virulence of the new Italian genotype.