According to the different transcripts between the dominant genotype (CHN-2H) and nondominant genotype (CHN-2A), four infectious molecular clones of the nondominant genotype (CHN-2A) were constructed by site-directed mutagenesis technique.

• CHN-2A还具有CHN-2H所不具备的另外两个RNA(命名为Reps和AD)。