Development of antibacterial vaccines provides an attractive approach for fighting bacterial diseases. Polysaccharides (PSs), forming a layer surrounding bacterial cell, represent a major, strain-specific virulence factor of bacterial pathogens. A variety of surface-located PS and its conjugates with carrier proteins have been used as vaccines for preventing bacterial infections. However, the PS-protein conjugate vaccines produced by current chemical methods are through empirical processes which result in a randomly connected mixture of the PS and the protein. There had been hardly any structure-activity relationship (SAR) studies of the PS-protein conjugate vaccines. In our lab, we are fusing the PS biosynthetic pathway with a bacterial N-glycoprotein biosynthetic pathway together to produce glycoprotein vaccines through one-pot fermentation. With the PS biosynthesis gene cluster, pglB and carrier protein gene acrA, each in one vector, fermentation of the recombinant E. Coli K-12 strain can produce structurally well defined, pure PS-protein conjugates for biological evaluation. For example, we produced several mg fully purified E. coli O157 O-antigen PS conjugated with AcrA from simple E. coli fermentation. The SARs of PSs and carrier proteins are being investigated by changing the length of PS, the size of the carrier protein, the density of PS on the carrier protein, and by fusing an immunologically active peptide epitope onto the carrier protein. In summary, our production of PS-protein conjugate vaccines through one-pot fermentation of recombinant E. coli provides an economical approach to synthesize structurally well defined glycoconjugates for both research and development of antimicrobial vaccines.

Production of polysaccharide-protein conjugate vaccines through synthetic biology

244th National Meeting (2012)

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