Host responses in laying hens following infectious bronchitis vaccination: Comparison of two vaccination strategies
Date
2021-06-03
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Abstract
The infectious bronchitis virus (IBV) causes infectious bronchitis (IB) and causes nephritis and reproductive tract abnormalities depending on the infecting IBV strain. Vaccination for the control of IB has been practiced for decades. Although it has been shown that administration of inactivated vaccine following priming with live attenuated vaccines in pullets induces protection of laying hens against IB, the immunological basis of this protective response has not been investigated adequately. The first objective was to inactivate and formulate the IBV Massachusetts (Mass) variant that was isolated from a flock with shell-less egg syndrome (SES) as an in-house adjuvanted vaccine and test whether it induces an antibody-mediated immune response. Although we observed that the in-house adjuvanted inactivated IBV Mass variant vaccine induces a positive antibody-mediated immune response, it does not induce an antibody-mediated immune response similar to that of a commercial inactivated IBV Mass vaccine. The second objective of the study was to compare two vaccination strategies adopted by the Canadian poultry industry in terms of their ability to induce an adequate immune response in the IBV-impacted tissues in laying hens. Vaccination strategy 1 (multiple live attenuated vaccines) and vaccination strategy 2 (combination of live attenuated vaccines given multiple times and one inactivated vaccine) were given to pullets between 3 and 16 weeks of age. Serum anti-IBV antibodies, recruitment of T cell subsets, and interferon (IFN)-γ mRNA expression were measured at 10 weeks post-last vaccination, in selected tissues. We observed that vaccination strategy 2 induced higher serum anti-IBV antibody response and IFN-γ mRNA expression in the lungs, kidneys and reproductive tract. Both vaccination strategies 1 and 2 recruited CD4+ T cells in the lungs and isthmus and CD8+ T cells in all the examined tissues except the uterus. Serum collected from chickens vaccinated with vaccination strategy 2 was able to neutralize the IBV Mass variant that caused SES in Western Canadian layers, indicating the potential ability of vaccination strategy 2 to protect laying hens against this IBV variant. Overall, our findings indicate that administration of live attenuated vaccines followed by an inactivated vaccine, induces better host responses in laying hens.
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Keywords
Infectious bronchitis virus, laying hen, infectious bronchitis vaccine, cell-mediated immune response, antibody-mediated immune response
Citation
Buharideen, S. M. (2021). Host responses in laying hens following infectious bronchitis vaccination: Comparison of two vaccination strategies (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.