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bioRxiv · 10.1101/2024.08.23.609347

Rhamnose Polysaccharide-Decorated Outer Membrane Vesicles as a Vaccine Candidate Targeting Group A Streptococcus from Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis

Ajay Castro, S.·Thomson, S.·Shaw, H. A.·Zorzoli, A.·Meyer, B. H.·Reglinski, M.·Dorfmueller, H. C.
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Abstract

Group A Streptococcus (Strep A) cause a wide range of human-exclusive infections, annually killing more than 500,000 people. Antibiotic resistance incidence of invasive Strep A tripled in the past decade and emphasises the need to develop a universal Strep A vaccine. In this study, we developed recombinant rhamnose polysaccharides (RhaPS), a validated universal Strep A vaccine candidate, presented on E. coli outer membrane vesicles (OMVs). We investigated OMV-RhaPS for their immunogenicity in the mouse and rabbit models. Through flow cytometry, ELISA, Luminex assays, and immunofluorescence microscopy, we demonstrated that RhaPS-specific antibodies recognise Strep A strains via the Group A Carbohydrate (GAC) in S. pyogenes and the newly emerged S. dysgalactiae subsp. equisimilis. Elevated IL-17a levels from RhaPS-OMV-immunised splenocytes indicate the RhaPS-specific stimulation of long-term memory immune cells. We are the first to report the efficacy and potency of recombinant produced RhaPS inducing humoral-mediated immune responses and triggering antibodies that recognise Strep A bacteria.

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Ajay Castro, S., Thomson, S., Shaw, H. A., Zorzoli, A., Meyer, B. H., Reglinski, M., Dorfmueller, H. C.. 2024-08-23. Rhamnose Polysaccharide-Decorated Outer Membrane Vesicles as a Vaccine Candidate Targeting Group A Streptococcus from Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis. https://doi.org/10.1101/2024.08.23.609347

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