Digesting pLXSN-mB7-1 by enzyme XhoI and BamHI to gain the opened plasmid pLXSN-mB7-1 with ambly end and BamHI sticking end; Inserting IRES-mB7-2 gene fragment into it to gain the double expressing vector pLXSN-mB7-1-IRES-mB7-2;

• 3XhoI酶切质粒pLXSN-mB7-1,末端钝化,然后BamHI再酶切,形成含钝末端和BamHI粘末端的开环pLXSN-mB7-1质粒,将IRES-mB7-2基因片段插入其中,得到pLXSN-mB7-1-IRES-mB7-2双表达载体;