A lot of point mutations were found in the S1 gene and N gene of the IBV isolates. In addition, a insertion mutation of 21-nt were found in the S1 gene of two IBV isolates, SC021202 and J.

• 在分离株的S1基因和N基因序列中均发现了大量散在的点突变,而且在SC021202株和J株的Sl基因中发现一段长21nt的插入片段,在以前的毒株中不存在。