Pathological, Immunohistochemical, and Molecular Study of Avian Infectious Bronchitis Virus in Egypt

INFECTIOUS BRONCHITIS is one of the most prevalent viral diseases affecting poultry, caused by avian infectious bronchitis virus (IBV), which induced a significant financial loss to the global poultry sector. This study investigated the occurrence of infectious bronchitis virus in diseased commercial broiler farms in six Egyptian governorates between January 2021 till December 2023. During the examination period, samples from trachea and its bifurcation, lungs, and kidneys were collected from 287 diseased broiler flocks, suffering from respiratory disorders, and having considerable mortalities. Flocks were then exposed to gross, microscopic, immunohistochemistry, and Real-time polymerase chain reaction (Real-time PCR) examinations. Data from this study has shown that prevalence of IBV was 54.7% as confirmed by Real-time PCR. Gross examination revealed severe respiratory lesions with caseous plug at the tracheal bifurcation and nephritis. Histopathological examination revealed varying degrees of respiratory and renal tissues degeneration, necrosis, and inflammation. Immunohistopathological examination revealed elevated expression of (IL-1 beta, and TNF alpha) and apoptotic markers (caspase-3 & BAX). Lesions were more obvious in the respiratory system than in kidney. The persistent existence of IBV in Egypt's poultry flocks highlights the necessity of routinely monitoring of IBV and revising control and vaccination protocols.