[4][5] IBV affects the performance of both meat-producing and egg-producing chickens and is responsible for substantial economic loss within the poultry industry.

[3] IBV is in the genus Gammacoronavirus,[7] or group 3,[6] with a non-segmented, positive-sense single-stranded RNA genome.

[12][13] When inhaled, virus will attach to glycoprotein receptors containing sialic acid on ciliated epithelial cells of the respiratory epithelium.

Local virus replication will result in viremia, spreading the infection into other tissues and organs.

At gross examination, kidneys may appear swollen and pale in color and with urates in ureters In hens, the viremic IBV will also reach the oviduct, causing lesions in the magnum (the egg-white gland) and in the uterus (the egg-shell gland), leading to a sharp decline of egg production, shell-less, fragile or roughened shells eggs (uterus lesion) with watery whites (magnum lesion).