Ten strains of adult specific pathogen free chickens are inoculated with Laryngotracheitis(ILT) virulent virus,to in vestigate the clinical signs and the pathological changes by autopsy.

• 用传染性喉气管炎（ILT）强毒株感染10个家系150日龄BWEL?SPF鸡，观察比较临床症状和剖检所见病变；