Supplementary file 1_Development and evaluation of a dual-target glycoconjugate against Shigella sonnei.docx

Antibody responses were measured and compared by ELISA. </p>Results<p>When co-produced in E. coli, PglS was able to transfer the cloned S. sonnei O-antigen onto three carrier proteins, modified to accept glycans from the PglS transferase enzyme—ExoA and two immunogenic Shigella-specific outer membrane proteins, EmrK and MdtA. Production of MdtA or ExoA glycoconjugates for immunisation studies utilised successive rounds of anion exchange chromatography, to remove unglycosylated material and obtain highly purified glycosylated proteins.

Analysis of murine sera following immunisation revealed an IgG response was raised against both carrier protein and the S. sonnei O-antigen for each glycoconjugate. </p>Discussion<p>A novel, conserved Shigella protein can be utilised as an effective carrier for the S. sonnei O-antigen to generate a Shigella-specific glycoconjugate that elicits IgG responses to both carrier protein and S. sonnei O-antigen.</p>