Despite the fact that vaccine resistance has been typically considered a rare phenomenon, some episodes of vaccine failure have been reported with increasing frequency in intensively-raised livestock. Infectious bronchitis virus (IBV) is a widespread avian coronavirus, whose control relies mainly on extensive vaccine administration. Unfortunately, the continuous emergence of new vaccine-immunity escaping variants prompts the development of new vaccines. In the present work, a molecular epidemiology study was performed to evaluate the potential role of homologous vaccination in driving IBV evolution. This was undertaken by assessing IBV viral RNA sequences from the ORF encoding the S1 portion of viral surface glycoprotein (S) before and after the introduction of a new live vaccine on broiler farms in northern-Italy. The results of several biostatistics analyses consistently demonstrate the presence of a higher pressure in the post-vaccination period. Natural selection was detected essentially on sites located on the protein surface, within or nearby domains involved in viral attachment or related functions. This evidence strongly supports the action of vaccine-induced immunity in conditioning viral evolution, potentially leading to the emergence of new vaccine-escape variants. The great plasticity of rapidly-evolving RNA-viruses in response to human intervention, which extends beyond the poultry industry, is demonstrated, claiming further attention due to their relevance for animal and especially human health.

中文翻译：

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同源疫苗接种后传染性支气管炎病毒在野外的进化。

尽管疫苗耐药性通常被认为是一种罕见现象，但在集约化饲养的牲畜中，一些疫苗失败事件的报道越来越频繁。传染性支气管炎病毒（IBV）是一种广泛传播的禽冠状病毒，其控制主要依靠广泛的疫苗接种。不幸的是，新疫苗免疫逃逸变种的不断出现促使新疫苗的开发。在目前的工作中，进行了一项分子流行病学研究，以评估同源疫苗接种在驱动 IBV 进化中的潜在作用。这是通过在意大利北部的肉鸡场引入新的活疫苗之前和之后评估编码病毒表面糖蛋白 (S) S1 部分的 ORF 的 IBV 病毒 RNA 序列来进行的。多项生物统计学分析的结果一致表明，疫苗接种后阶段存在较高的压力。自然选择主要在蛋白质表面、参与病毒附着或相关功能的区域内或附近的位点上进行检测。这一证据有力地支持了疫苗诱导的免疫在调节病毒进化中的作用，可能导致新的疫苗逃逸变体的出现。快速进化的 RNA 病毒在应对人类干预方面具有巨大的可塑性，这种干预范围超出了家禽业，这已得到证明，由于它们与动物尤其是人类健康的相关性，因此受到了进一步的关注。