Comparative histopathology of three Serotypes of live infectious bronchitis vaccine (IB88 – 4/91 – H120) in broiler chickens

Abstract

Infectious bronchitis in birds, caused by a corona virus, is a highly contagious viral disease that causes economic losses in the poultry industry worldwide. It affects the respiratory, urinary, and genital tracts, with control and prevention focused on vaccination and biosecurity measures.

This study aims to compare histopathological lesions caused by IB88, H120, and IB4-91 vaccines in broiler chickens aged 1 to 5 days. One hundred ROSS308 chickens were divided into four groups, with each group receiving a different vaccine or serving as a control. Group 1 received the IB4-91 vaccine, group 2 was administered the H120 vaccine, group 3 received the IB88 vaccine, while group 4 served as the control group. Over a period of five days starting from the second day, five chickens from each group were randomly selected and humanely euthanized. Histopathological samples were collected from the trachea, lungs, and kidneys, processed into slides, and examined under an optical microscope for comparative analysis.

Significant differences were observed in the comparison of the control group with the vaccinated groups in terms of various histopathological indicators. These included hyperemia and infiltration of inflammatory cells in the kidney, lung hyperemia, infiltration of inflammatory cells, necrosis of respiratory epithelium, and hyperplasia of tracheal mucous cells. Notably, differences were noted between the IB4-91 and H120 groups in terms of inflammatory cell infiltration, respiratory epithelium necrosis, tracheal mucous cell hyperplasia, and renal hyperemia. Similarly, variations were observed between the IB88 and H120 groups in terms of respiratory epithelium necrosis and tracheal inflammatory cell infiltration. Furthermore, differences were identified between the IB4-91 and IB88 groups concerning tracheal mucosal hyperplasia and renal hyperemia. These findings highlight distinct histopathological responses induced by different vaccines in broiler chickens and emphasize the importance of vaccine selection in poultry health management.