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1.76亿只鸟和96亿个鸡蛋，为国民经济贡献了49亿美元。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，特别是餐蛋业具有重要的经济意义。IBV可在雏鸡和成鸡中复制，根据感染IBV的菌株不同，可在呼吸系统、生殖系统和泌尿系统观察到原发性病变。因此，IBV感染可能导致雏鸡死亡，降低产蛋量和蛋鸡质量，限制家禽生产的盈利能力。为控制IBV引起的临床疾病，可使用减毒活疫苗。新的“变种”和更异质的IBV毒株的出现，导致接种疫苗的鸡群暴发传染性支气管炎（IB），造成重大的生产损失。这是由于缺乏交叉保护免疫的发展。在加拿大东部和西部，也观察到影响鸡蛋生产的蛋鸡中出现了类似的IB疫情。导致产蛋异常的主要IBV变异在加拿大西部和东部是不同的。在加拿大东部，自2017年以来，由德尔马瓦（DMV）变异IBV引起的假层综合征（FLS）一直是一个问题。已分离到FLS病原IBV菌株，进行了分子表征，并建立了实验模型。在拟议的项目中，我们将优化疫苗接种策略，针对从加拿大东部饲养的鸡中分离的DMV IBV变异引起的FLS和其他产蛋异常，使用加拿大现有的IBV疫苗。然后，我们将为加拿大家禽业的利益提出基于疫苗的控制策略。

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.