Chimeric oligosaccharide conjugate induces opsonic antibodies against Streptococcus pneumoniae serotypes 19A and 19F

Someswara Rao Sanapala; Bruna M S Seco; Ju Yuel Baek; Shahid I Awan; Claney L Pereira; Peter H Seeberger

doi:10.1039/d0sc02230f

Chimeric oligosaccharide conjugate induces opsonic antibodies against Streptococcus pneumoniae serotypes 19A and 19F

Chem Sci. 2020 Jun 26;11(28):7401-7407. doi: 10.1039/d0sc02230f.

Authors

Someswara Rao Sanapala¹, Bruna M S Seco^{1

2}, Ju Yuel Baek¹, Shahid I Awan¹, Claney L Pereira², Peter H Seeberger^{1

2}

Affiliations

¹ Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces Am Mūhlenberg 1 D-14424 Potsdam Germany peter.seeberger@mpikg.mpg.de.
² Department of Chemistry and Biochemistry, Freie Universität Berlin Arnimallee 22 D-14195 Berlin Germany.

Abstract

Streptococcus pneumoniae 19A (ST19A) and 19F (ST19F) are among the prevalent serotypes causing pneumococcal disease worldwide even after introduction of a 13-valent pneumococcal conjugate vaccine (PCV13). Synthetic glycoconjugate vaccines have defined chemical structures rather than isolated polysaccharide mixtures utilized in marketed vaccines. Ideally, a minimal number of synthetic antigens would cover as many bacterial serotypes to lower cost of goods and minimize the response to carrier proteins. To demonstrate that a chimeric oligosaccharide antigen can induce a protective immune response against multiple serotypes, we synthesized a chimeric antigen (ST19AF) that is comprised of a repeating unit of ST19A and ST19F capsular polysaccharide each. Synthetic glycan epitopes representing only ST19A, and ST19F were prepared for comparison. Semisynthetic glycoconjugates containing chimeric antigen ST19AF induced high antibody titers able to recognize native CPS from ST19A and ST19F in rabbits. The antibodies were able to kill both strains of pneumococci. Chimeric antigens are an attractive means to induce an immune response against multiple bacterial serotypes.