Viruses were grown in embryonated hen eggs and the viral RNA was extracted from allantoic fluid. The partial PB1 polymerase gene fragments were amplified by RT-PCR,and the purified PCR products were sequenced using the CEQ sequence kit by direct method.

• 方法 病毒在鸡胚中传代 ,自收获的尿囊液提取RNA ,通过RT-PCR ,扩增聚合酶PB1基因片段 ,并进行序列测定 ,测序结果采用PHYLIP软件在Internet网上分析处理 ,并用TreeView软件绘制系统进化树。