Multicomponent Vaccines against Group A Streptococcus Can Effectively Target Broad Disease Presentations

Abstract

Group A Streptococcus (GAS) is an important global human pathogen, with a wide range of disease presentations, from mild mucosal infections like pharyngitis to invasive diseases such as toxic shock syndrome. The effect on health and mortality from GAS infections is substantial worldwide, particularly from autoimmune sequelae-like rheumatic heart disease (RHD), and there is currently no licenced vaccine. We investigated protein antigens targeting a broad range of GAS disease presentations as vaccine components in individual and combination formulations. The potency and functional immunity generated were evaluated and compared between groups. Antibodies against all components were found in pooled human IgG (IVIG) and an immune response generated following the subcutaneous immunisation of mice. A combination immunisation showed a reduction in IgG response for SpyCEP but an increase for Cpa and Mac-1 (IdeS). An opsonophagocytosis assay (OPA) showed the killing of GAS with immune sera against M protein and combination groups, with a lower killing activity observed for immune sera against other individual antigens. Specific antigen assays showed functional immunity against SpyCEP and Mac-1 from both individual and combination immunisations, with the activity correlating with antibody titres. However, efficient blocking of the binding activity of Cpa to collagen I and fibronectin could not be demonstrated with immune sera or purified IgG. Our data indicate that combination immunisations, while effective at covering a broader range of virulence factors, can also affect the immune response generated. Further, our results showed that an OPA alone is inadequate for understanding protection from vaccination, particularly when considering protection from immune evasion factors and evaluation of the colonisation leading to pharyngitis.

Streptococcus pyogenescolonization in children aged 24-59 months in The Gambia: Impact of Live Attenuated Influenza Vaccine and associated serological responses

“…We also demonstrate that asymptomatic S. pyogenes colonization leads to seroconversion to several antigens representative of different stages in S. pyogenes infection, with differences in antibody magnitude across the different targets measured[14]. Higher serological responses to S. pyogenes antigens were observed in children colonized at any timepoint in our study compared to non-colonized controls.…”

“…The data provide further evidence that the impact of LAIV on colonization with potentially pathogenic bacteria is only modest and supports the wider rollout of LAIV to reduce influenza disease and its complications in LMICs. We also demonstrate that asymptomatic S. pyogenes colonization leads to seroconversion to several antigens representative of different stages in S. pyogenes infection, with differences in antibody magnitude across the different targets measured [14]. Higher serological responses to S. pyogenes antigens were observed in children colonized at any timepoint in our study compared to non-colonized controls.…”

“…Antibody measurement: Blood was collected in serum separation tubes from participants in the LAIV group, for study endpoints on influenza vaccine immunogenicity [11]. [14]. Blocking and serum dilution was performed using 1% casein blocking buffer (ThermoFisher Scientific, USA).…”

“…96-well flat-bottomed high binding ELISA plates were coated overnight with several recombinant proteins in pH 9.6 carbonate buffer: S. pyogenes cell envelope protease (SpyCEP) at 0.16μg/ml, S. pyogenes Adhesion and Division protein (SpyAD) at 1μg/ml, M1 protein at 0.5μg/ml, Mac/IdeS protein (henceforth referred to as Mac) at 1 μg/ml, and Collagen binding protein (Cpa) at 0.16 μg/ml. Proteins were provided by National Institute for Biological Standards and Control, MHRA, UK (Supplementary data) [14]. Blocking and serum dilution was performed using 1% casein blocking buffer (ThermoFisher Scientific, USA).…”

A platform for the recombinant production of Group A Streptococcus glycoconjugate vaccines

“…All tested dilutions from Day 70 bleed showed that the IdeS protease activity was neutralised to >70% (Fig. 5C) and exceeded the neutralisation ability of a positive control sample from previous IdeS immunisation [64]. The data suggests that IdeS-RhaPS could provide a dual-hit vaccine candidate, targeting the Strep A surface carbohydrate and the secreted protease IdeS.…”