Conjugation Mechanism for Pneumococcal Glycoconjugate Vaccines: Classic and Emerging Methods

Abstract

Licensed glycoconjugate vaccines are generally prepared using native or sized polysaccharides coupled to a carrier protein through random linkages along the polysaccharide chain. These polysaccharides must be chemically modified before covalent linking to a carrier protein in order to obtain a more defined polysaccharide structure that leads to a more rational design and safer vaccines. There are classic and new methods for site-selective glycopolysaccharide conjugation, either chemical or enzymatic modification of the polysaccharide length or of specific amino acid residues of the protein carrier. Here, we discuss the state of the art and the advancement of conjugation of S. pneumoniae glycoconjugate vaccines based on pneumococcal capsular polysaccharides to improve existing vaccines.

A bioconjugate vaccine against Brucella abortus produced by engineered Escherichia coli

“…Conjugate vaccines produced by covalently linking these bacterial surface polysaccharides to proteins have shown very good protection against infections, and some have been approved for marketing, such as PREVNAR ® 13 produced by Pfizer (Berti and Adamo, 2018). The classic preparation methods of conjugate vaccines involve chemical cross-linking and require the extraction and purification of bacterial polysaccharides, carrier proteins, and final cross-linked products (Berti and Adamo, 2018;Mettu et al, 2020;Morais and Suarez, 2022), leading to the relatively high cost. In addition, the extraction of antigenic polysaccharides requires the fermentation of Brucella, posing biosafety risks.…”