A亚群禽白血病病毒囊膜基因gp85片段在大肠杆菌中的表达

将RAV－1囊膜基因gp85片段来克隆到表达质粒pET-21d( )中得到重组表达质粒pET-21d-RAV-1env(BelⅡ/SalⅠ）序列分析表明该插入片段的核苷酸序列和阅读框都与RAV－1囊膜基因相应序列相同。用其转化大肠杆菌BL21（DE）3并经IPTG诱导，SDS－PAGE分析表明RAV－1囊膜基因融合蛋白表达产物约20kD，与理论值相符；IPTG诱导起始时间比诱持续时间对表达量的影响更大。

Expression of Envelope Gene gp85 of Avian Leukosis Virus in E.coli

A part of the cloned fragment was excised from the recombinant with Bgl II and Sal I and subcloned into the expression vector pET-21d ( ) to yield another recombinant named pET-21d-RAV-1 env (Bgl II/Sal I). The recombinant was sequenced and the result showed that the inserted fragment was identical to the counterpart in RAV-1 env gene both in nucleotide sequence and open reading frame. The E.coli BL2 (DE3) transformed with recombinant plasmid were induced with 1 mmol/L IPTG and the expression product found to be 20 kD in size on SDS-PAGE. The size of the expression product was the same as that theoretically calculated. In addition, the effects of start time and duration for IPTG induction on expression efficiency were analyzed and the result indicated that the start time for IPTG induction was more important to high expression efficiency than its duration.