The signal peptide sequence which was used for secretedly expressing divergent gene in mammary gland cells was ligated to the e2 gene , the e2 gene with signal sequence was obtained by pcr . the gene resisting kanamycin was cut down from pgfp - cl vector and inserted into p22 vector , a p22 vector with gene resisting kanamycin was constructed , it was tried to construct an expression vector for transforming go 猪瘟病毒ez基因的乳腺特异表达载体构建:将在乳腺细胞中特异分泌的信号肽序列连接到ez基因, pcr得到了目的片段,再将pgfpci载体上的kana基因切下与在乳腺细胞中特异表达的p22载体连接,使其带有筛选标记,然后将带有信号肽的ez插入到p22中,试图构建山羊乳腺上皮细胞的特异性表达载体。