Biosynthesis of polysaccharide conjugate vaccines against Klebsiella pneumoniae serotype O2 strains

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.