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Abstract
In traditional glycoconjugate vaccine preparations, the capsular polysaccharide (CPS) ofpathogenic bacteria is covalently attached to a known-immunogenic carrier protein, allowing for
activation of the body’s adaptive immune system. This results in the generation of CPS-specific
IgG antibody secreting plasma cells and the formation of immunological memory, hallmarked by
success in the clinical space by providing protection to at-risk groups for decades. However, the
efficacy of these glycoconjugate preparations is variable due to ill-defined and destructive
chemistries, further leading to inconsistent dosage responses between vaccine preparations and
bacterial serotypes. To better combat the empirical vaccinology approach currently being
utilized, a shift to a knowledge-based strategy harnessing the mechanistic insights garnered from
recent advances in glycoimmunology is being explored. The previous discovery that
glycoconjugates are taken up by antigen-presenting cells and utilized, first through degradation
into glycopeptides, then presentation of the carbohydrate epitope to the T cell by association with
Major Histocompatibility Complex class II molecules, allows for more rational approaches in
vaccine design. To this end, glycoconjugate molecules using non-traditional methods are being
explored to expand the understanding and toolset in conjugate vaccine construction. In this
dissertation, we explored a novel chemoenzymatic route for the synthetic preparation of
glycoconjugate vaccines, using Streptococcus pneumoniae serotype 14 as a representative
pathogen. Additionally, the use of a recently described oligosaccharyltransferase, PglS, was used
to generate a protective multivalent group B Streptococcus conjugate through an E. coli
bioconjugate expression system. The overall objective of this work is to build and test nextgeneration glycoconjugate vaccines that have been formulated to combat the shortcomings of
previous glycoconjugates, thus highlighting the key factors in driving an adaptive immune
response and presenting alternative strategies for future vaccine preparations.