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

2019年，加拿大禽业年成交量为1.76亿只禽类和96亿只鸡蛋，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养殖业特别是肉鸡养殖业具有重要的经济意义。IBV在幼鸡和成年鸡中复制，根据感染IBV毒株的不同，在呼吸系统、生殖系统和泌尿系统观察到原发病变。因此，IBV感染可能导致雏鸡死亡，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IBV引起的临床疾病，可以使用减毒活病毒疫苗。新的“变种”和更多异质性IBV毒株的出现，已导致接种疫苗的鸡群中爆发传染性支气管炎(IB)，导致重大产量损失。这是由于缺乏交叉保护免疫的发展。加拿大东部和西部也观察到了影响产蛋量的蛋鸡爆发类似的IB疫情。在加拿大西部和东部，导致鸡蛋生产异常的主要IBV变种是不同的。在加拿大东部，由Delmarva(DMV)变种IBV引起的假层综合征(FLS)自2017年以来一直是一个问题。在拟议的项目中，我们将使用加拿大现有的IBV疫苗优化疫苗接种策略，以预防从加拿大东部饲养的鸡中分离出的DMV IBV变异导致的FLS和其他产蛋异常。然后，我们将提出基于疫苗的控制策略，以造福于加拿大的家禽业。

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.