A modular constitutive single-plasmid platform for efficient production of a recombinant Strep A glycoconjugate vaccine

Production of glycoconjugate vaccines has long relied upon chemical methods which are highly complex and expensive, resulting in vaccines that are not widely affordable. Heterologous bioconjugation methods, such as Protein-Glycan Coupling Technology (PGCT), have emerged as a path to significantly cheaper manufacture using safe host organisms, such as Escherichia coli , for recombinant glycoconjugate expression. PGCT glycoconjugate synthesis components are typically encoded across three plasmids and require the addition of exogenous chemical inducers for gene expression. In this study, we utilise modular DNA assembly to generate a single constitutive plasmid for biosynthesis of a Streptococcus pyogenes rhamnose polysaccharide glycoconjugate vaccine. This approach resulted in a greater than seven-fold glycoconjugate yield as well as simplified cell culture conditions compared to the traditional three plasmid inducible system. Importantly, given the modular nature of this method, this innovation could be applied to the manufacture of glycoconjugate vaccines against a range of pathogens.