O2血清型肺炎克雷伯氏菌多糖结合疫苗的生物合成

Biosynthesis of polysaccharide conjugate vaccines against Klebsiella pneumoniae serotype O2 strains

摘要:

本研究旨在利用微生物体内合成肺炎克雷伯氏菌 (Klebsiella pneumoniae，Kp) 多糖结合疫苗并研究其保护效果。通过敲除Kp O抗原连接酶基因waaL阻断其LPS合成，再向缺失株中导入糖基工程载体，使细菌能够在体内合成糖蛋白，并将该糖蛋白免疫小鼠后评价其保护效果。结果表明，在构建的 Kp waaL缺失株中导入糖基工程载体后，底物蛋白重组霍乱毒素B亚单位rCTB (Recombinant cholera toxin B subunit) 能够被O糖化，从而得到糖蛋白；动物实验结果显示该疫苗能刺激小鼠产生较高的抗体效价，试验组小鼠攻毒后一周存活率可达75%。这种生物合成方法制备的多糖结合疫苗有望成为针对肺炎克雷伯氏菌的新型候选疫苗。

Abstract:

The main purpose of this research is to synthesize and evaluate a new glycoconjugate vaccine against Klebsiella pneumonia (Kp). First, the gene (waaL) responsible for the expression of O antigen ligase was deleted to block the synthesis of bacterial LPS. Then the vector that encodes a glycosyltransferase (PglL) was transferred into the mutant. The enzyme PglL could catalyze the transfer of OPS units to recombinant cholera toxin B subunit (rCTB) to form glycoproteins in vivo. The protective effects of the glycoproteins were studied by the mice models with acute bacteremia that were induced by intraperitoneal injection of wildtype Kp bacteria. The results were as followings: A Kp waaL mutant was obtained and the rCTB protein could be successfully glycosylated in the mutant. The vaccine can stimulate a high antibody titer in the mice sera with or without adjuvant. It can also protect mice from the lethal dose injection of Kp. The survival rate of vaccine candidate groups could reach 75%. The glycoconjugate vaccine candidate prepared by this biosynthetic method is expected to become a novel effective vaccine against Klebsiella pneumoniae.