Coronaviridae: Infectious Bronchitis Virus

Abdel-Moneim, Ahmed S.

The abstract is published online only. If you did not include a short abstract for the online version when you submitted the manuscript, the first paragraph or the first 10 lines of the chapter will be displayed here. If possible, please provide us with an informative abstract. Avian infectious bronchitis virus is the prototype of the gammacoronavirus, which is responsible for highly contagious disease in chicken. It continues to be one of the most common diseases in chicken and probably endemic in all countries that raise chicken. The virus infection causes considerable economic losses in both commercial meat- and egg-type birds. The virus tropism includes respiratory tract, proventriculus, cecal tonsils, oviduct and kidney. Infections mainly cause respiratory distress in young chickens. In broiler chicken,the virus causes respiratory distress but some strains produce interstitial nephritis while others cause proventriculitis. In laying hens, the virus causes considerable decrease in egg production and quality. Antigen detection and the reverse transcription polymerase chain reaction (RT-PCR) are commonly used methods for rapid virus diagnosis. RT-PCR and direct gene sequence of the S1 gene or restriction fragment length polymorphism (RFLP) are used for virus genotyping. The control strategy against infectious bronchitis virus (IBV) is conducted by live attenuated vaccine. To date, more than 65 genotypes and variants are characterized worldwide with poor cross protection. In addition, recombination could increase the variety of strains since live attenuated IBV vaccine viruses may recombine with virulent wild-type strains, and the resultant viruses have caused outbreaks of respiratory disease and production problems in chicken flocks.