Pathogenesis and host responses in lungs and kidneys following Canadian 4/91 infectious bronchitis virus (IBV) infection in chickens

Abstract

The infectious bronchitis virus (IBV) 4/91 was one of the common IBV variants isolated in Eastern Canada between 2013 and 2017 from chicken flocks showing severe respiratory and production problems. We designed an in vivo experiment, using specific pathogen free (SPF) chickens, to study the pathogenesis of, and host response to, Canadian (CAN) 4/91 IBV infection. At one week of age, the chickens were infected with 4/91 IBV/Ck/Can/17-038913 isolate. Swab samples were collected at predetermined time points. Five birds from the infected and the control groups were euthanized at 3, 7- and 10-days post-infection (dpi) to collect lung and kidney tissues. The results indicate IBV replication in these tissues at all three time points with prominent histological lesions, significant immune cell recruitment and up regulation of proinflammatory mediators. Overall, our findings add to the understanding of the pathogenesis of 4/91 infection and the subsequent host responses in the lungs and kidneys following experimental infection.

Keywords: CD4+ T cell; CD8+T cell; Cytokine mRNA expression; Cytokines; Infectious bronchitis virus; Macrophage; Young chicken.