Bioconjugation as a promising method for vaccine development

Introduction. Bioconjugation, or protein glycan coupling technology, PGCT, is a method for creating carbohydrate-protein composites based on the ability of certain bacteria to perform eukaryotic-type glycosylation. This method allows for the production of glycoproteins directly in the cells of producer bacteria, most often Escherichia coli, bypassing the stage of chemical conjugation. This significantly simplifies the creation and production of conjugated vaccines, consisting of polysaccharide antigens combined with a protein carrier that performs the functions of a T-cell antigen and an adjuvant. The aim of the review is to analyze and summarize current data on both the bioconjugation method itself and the underlying biochemical processes, as well as on the vaccines being developed using this method. The preparation of the review involved studies presented in the PubMed, Scopus, Google Scholar, eLIBRARY.RU databases as of February 2025. The following keywords were used for the search: bioconjugation, vaccines, PGCT, conjugated vaccines, bacterial glycosylation. An analysis of literature sources dedicated to the study of bacterial N-glycosylation, on the basis of which the bioconjugation technology was developed, as well as similar processes occurring in certain bacterial species, was conducted. Reports on the development of new vaccines and the improvement of existing vaccines against the most relevant pathogens have been analyzed. At present, vaccination appears to be the most effective way to combat infectious diseases, including efforts to counter the spread of antibiotic-resistant microorganisms. The diversity of pathogens encountered by the human population compels the search for multiple approaches of creating effective and safe vaccines. Simplifying and reducing the cost of producing new drugs allows for a more confident response to the threat of new epidemics. Bioconjugation helps create new vaccines and improve existing vaccines, although there are certain limitations. Conclusion. Modern vaccine production is characterized by a variety of approaches united by a single goal — to effectively counter the threats of new epidemics. Bioconjugation is one of the new, yet quite promising methods through which several vaccine candidates are already being developed. The analysis of the current state of these projects may be useful in choosing an approach for developing subsequent preventive immunological drugs.