A novel variant of the infectious bronchitis virus resulting from recombination events in Italy and Spain
A novel variant of the infectious bronchitis virus resulting from recombination events in Italy and Spain
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DOI：
10.1080/03079457.2016.1200011
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发表时间：
2017-01-01
期刊：
影响因子：
2.8
通讯作者：
Cecchinato, M.
中科院分区：
文献类型：
--
作者：
Moreno, Ana;Franzo, G.;Cecchinato, M.
传染性支气管炎被认为是家禽中最具破坏性的疾病之一。控制其传播通常是通过生物安全措施和广泛的疫苗接种来尝试的。然而，该病毒的显著遗传和抗原变异性（其源自突变和重组事件）代表了该疾病的未解决的挑战。本研究报告了2012年至2014年期间在意大利和西班牙检测到的重组簇的出现和传播。共36个西班牙和意大利传染性支气管炎病毒（IBV）现场株进行了调查和遗传特征的完整S1基因的系统发育，分子，重组和选择压力分析。根据部分S1序列测定，27株来自西班牙的IBV和9株来自意大利的IBV与广东/新大地（XDN）基因型密切相关。完整的S1基因的系统发育分析表明，XDN株形成了一个同质的分支与西班牙IBV分离株内的QX基因型，而意大利株内有较高的变异性。分离分析表明，这些毒株分属于4个不同的群，它们分别来自于QX和793 B基因型之间的独立重组事件。我们的数据支持两种不同的情况下的假设：第一，在西班牙，大型和同质的分支可能起源于一个单一的后代的重组创始人，成为占主导地位，并蔓延到全国各地。其次，9个意大利重组体，其特征在于三种不同的重组模式，可能代表不太适合的菌株，因为他们是不太可行的重组父母。
Infectious bronchitis is considered to be one of the most devastating diseases in poultry. Control of its spread is typically attempted through biosecurity measures and extensive vaccination. However, the remarkable genetic and antigenic variability of the virus, which originate from both mutations and recombination events, represents an unsolved challenge for this disease. The present study reports on the emergence and spread of recombinant clusters detected in Italy and Spain between 2012 and 2014. A total of 36 Spanish and Italian infectious bronchitis virus (IBV) field strains were investigated and genetically characterized using phylogenetic, molecular, recombination and selection pressure analyses of the complete S1 gene. Based on the partial S1 sequencing, 27 IBV strains originating from Spain and nine from Italy were initially classified as being closely related to the Guandong/Xindadi (XDN) genotype. Phylogenetic analysis of the complete S1 gene revealed that the XDN strains formed a homogeneous clade with the Spanish IBV isolates within the QX genotype, whereas there was higher variability within the Italian strains. Recombination analysis determined that these strains belonged to four groups, which originated from independent recombination events between the QX and 793B IBV genotypes. Our data support the hypothesis of two different scenarios: firstly, in Spain, the large and homogeneous clade probably originated from a single offspring of the recombinant founder, which became dominant and spread throughout the country. Secondly, the nine Italian recombinants, which are characterized by three different recombination patterns, probably represent less fitted strains, because they were less viable with respect to their recombinant parents.