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

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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.