| Avian infectious bronchitis virus | |
|---|---|
| Virus classification | |
| Group: | Group IV ((+)ssRNA) |
| Order: | Nidovirales |
| Family: | Coronaviridae |
| Genus: | Coronavirus |
| Species: | Avian infectious bronchitis virus |
Avian infectious bronchitis virus (IBV) [1] is a coronavirus which infects chicken, causing the associated disease, infectious bronchitis (IB. It is a highly infectious avian pathogen which affects the respiratory tract, gut, kidney and reproductive systems of chickens.[1][2]
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IBV is a coronavirus, recently relocated to genus Gammacoronavirus [2], with a non-segmented, positive-sense single-stranded RNA genome.[3]
When inhaled, virus will attach to glycoprotein receptors containing sialic acid on ciliated epithelial cells of the respiratory epithelium. The respiratory replication will result in loss of ciliary activity [3], mucus acumulation, necrosis and desquamation, causing respiratory distress, râles and asphyxia. Local virus replication will result in viremia, spreading the infection into other tissues and organs. Other respiratory diseases of chickens (Mycoplasma gallisepticum, avian infectious laryngotracheitisGallid herpesvirus 1, Newcastle disease, Avian metapneumovirus infection may be confused clinically to infectious bronchitis.
Through viremia, some nephrotropic strains (most of high virulence) could infect the kidney epithelium in tubules and nephron, causing kidney failure. At gross examination, kidneys may appear swollen and pale in color and with urates in ureters.
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. Infection of chickens at puberty, during the oviduct development, will impede oviduct formation and destroy future laying capacity, resulting in "false layers". However, other diseases affecting layer chickens could lead to that condition.[4]