Acute hypersensitive-like injury in specific-pathogen-free chickens after infection with very virulent infectious bursal disease virus.

Very virulent infectious bursal disease virus (vvIBDV) can cause systemic inflammatory syndromes and acute death in specific-pathogen-free chickens within 72 h. However, the subtle mechanism of these severe inflammatory responses has been unsatisfactorily resolved until now. This study determined the kinetics of mast cells, tryptase, eosinophilic major basic protein, and eotaxin expression in specific-pathogen-free chickens after vvIBDV infection. Results showed that mast cell population, tryptase activity, major basic protein, and eotaxin expression were increased markedly in the vvIBDV-infected animals compared with the controls, with a significant difference in the bursa. Acute inflammatory lesions and high mortality were observed in vvIBDV-infected chickens. These observations implicate activated mast cells and eosinophils as important participants in vvIBDV-induced acute inflammatory lesions through mediators released in a short timeframe.