Comparison revealed that the vaccine strains at 5P were identical to each other, but the S 79 strain at 25P appeared higher mutation rate than that of the Jeryl Lynn strain at 25P.

• 传代之前第5代的两种疫苗株的目的基因的核苷酸序列完全一致； 传至第25代的S79株的目的基因的核苷酸序列比25代的JerylLynn株显示了更高的突变率。