Optimization of vaccination strategies for table egg layers controlling egg production problems induced by currently circulating infectious bronchitis virus (IBV) variants

2019年，加拿大家禽业的年营业额为1.76亿只家禽和96亿枚鸡蛋，为国民经济贡献了49亿加元。由传染性支气管炎病毒（IBV）引起的呼吸道病毒感染对家禽业特别是蛋鸡业具有重要的经济意义。IBV在幼龄和成年鸡中复制，根据感染的IBV毒株，在呼吸、生殖和泌尿系统中观察到原发病变。因此，IBV感染可能导致雏鸡死亡，并降低蛋鸡的产蛋量和质量，限制家禽生产的盈利能力。为了控制由IBV引起的临床疾病，可获得减毒活病毒疫苗。新的“变体”和更异质的IBV毒株的出现导致了接种疫苗的鸡群中传染性支气管炎（IB）的爆发，从而导致显著的生产损失。这是由于缺乏交叉保护性免疫的发展。在加拿大东部和西部也观察到影响产蛋量的蛋鸡中类似的IB爆发。导致产蛋异常的主要IBV变种在加拿大西部和东部是不同的。在加拿大东部，自2017年以来，由Delmarva（DMV）变异IBV引起的假蛋鸡综合征（FLS）一直是一个问题。FLS的致病性IBV毒株已经分离、分子鉴定并建立了实验模型，在本研究中，我们将利用加拿大现有的IBV疫苗，优化针对FLS和其他产蛋异常的疫苗接种策略。然后，我们将提出基于疫苗的控制策略，为加拿大家禽业的利益。

In 2019, Canada's poultry industry has an annual turnover of 176 million birds and >9.6 billion eggs and contributed $4.9 billions to the national economy. A respiratory viral infection caused by infectious bronchitis virus (IBV) is economically important for poultry industry in general and table egg layer industry in particular. The IBV replicates in young and adult chickens and the primary lesions are observed in the respiratory, reproductive and urinary systems depending on the infecting IBV strain. Consequently, IBV infections may lead to mortality in young chickens and reduced egg production and quality in layers, limiting the profitability of poultry production. For the control of clinical disease caused by IBV, live attenuated viral vaccines are available. The emergence of new "variant" and more heterogeneous IBV strains, has led to infectious bronchitis (IB) outbreaks in vaccinated flocks resulting in significant production losses. This is due to the lack of development of cross protective immunity. Similar outbreaks of IB in layers affecting egg production have been observed in Eastern and Western Canada. The predominant IBV variants causing egg production abnormalities are different in Western and Eastern Canada. In Eastern Canada, false layer syndrome (FLS) caused by the Delmarva (DMV) variant IBV has been an issue since 2017. The causative IBV strains of FLS are isolated, molecularly characterized and experimental models are established already.In the proposed project, we will optimize vaccination strategies against FLS and other egg production abnormalities induced by DMV IBV variant isolated from chickens raised in Eastern Canada using currently available IBV vaccines in Canada. Then, we will propose vaccine based control strategies for the benefit of the poultry industry in Canada.