Biology subjects

Zorzoli, A.

Publications and source records attributed to Zorzoli, A..

3 recordsLinked to original sources

bioRxiv2024

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

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.

microbiology↗

bioRxiv2021

Recombinant Group A Carbohydrate backbone embedded into Outer Membrane Vesicles is a potent vaccine candidate targeting Group A Streptococcus from Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis

BackgroundGroup A Streptococcus (GAS) are responsible for a wide range of human-exclusive infections, annually killing more than 500,000 people. Antibiotic resistance incidence of invasive GAS tripled in the past decade and emphasises the need to develop a universal GAS vaccine. We have produced, for the first time, a recombinant polyrhamnose backbone (pRha), a validated universal GAS vaccine candidate. E. coli outer membrane vesicles (OMVs) carrying pRha were investigated for their immunogenicity and efficacy in an animal model. MethodsOMVs decorated with pRha were administered to C57BL/6J mouse and rabbit models. Flow cytometry, ELISA, Luminex, immunofluorescence microscopy and serum bactericidal assay assays were conducted to investigate the ability of pRha-specific antibodies to recognise and kill clinical (hypervirulent) GAS strains. ResultsOur results suggest that pRha-OMVs induce specific antibodies which recognise Group A Carbohydrate (GAC) from S pyogenes and S. dysgalactiae subsp. equisimilis. Increased IgG levels correlate with increased bactericidal killing of the hypervirulent GAS M89 strain. Elevated IL-17a from pRha-OMV-immunised splenocytes indicates possible stimulation of long-term memory immune cells. ConclusionWe are the first to report efficacy and potency of this unique, exogenously produced polysaccharide, pRha, in the induction of humoral-mediated immune responses to GAS. TopicStreptococcus pyogenes, immunoglobulins, polysaccharides, opsonophagocytosis, acute rheumatic fever, M protein, invasive Group A Streptococcus, hyaluronic acid

microbiology↗

bioRxiv2018

Identification of lead compounds targeting the dTDP-L-rhamnose biosynthesis pathway using Streptococcus pyogenes

Biosynthesis of the nucleotide sugar precursor dTDP-L-rhamnose is critical for the viability and virulence of many human pathogenic bacteria, including Streptococcus pyogenes (Group A Streptococcus; GAS) and Streptococcus mutans. Those pathogens require dTDP-L-rhamnose for the production of structurally similar rhamnose polysaccharides in their cell wall. Via heterologous expression in S. mutans, we confirm that GAS RmlB and RmlC are critical for dTDP-L-rhamnose biosynthesis through their action as dTDP-glucose-4,6-dehydratase and dTDP-4-keto-6-deoxyglucose-3,5-epimerase enzymes, respectively. Complementation with GAS RmlB and RmlC containing specific point mutations corroborated the conservation of previous identified catalytic residues in these enzymes. Bio-layer interferometry was used to identify and confirm inhibitory lead compounds that bind to GAS dTDP-rhamnose biosynthesis enzymes RmlB, RmlC and GacA. One of the identified compounds, Ri03, inhibited growth of GAS as well as several other rhamnose-dependent streptococcal pathogens with an MIC50 of 120-410 M. We therefore conclude that inhibition of dTDP-L-rhamnose biosynthesis such as Ri03 affect streptococcal viability and can serve as a lead compound for the development of a new class of antibiotics that targets dTDP-rhamnose biosynthesis in pathogenic bacteria.

microbiology↗