title: Combinatorial Synthetic Peptide Vaccine Strategy Protects against Hypervirulent CovR/S Mutant Streptococci.
abstract: Cluster of virulence responder/sensor (CovR/S) mutant group A streptococci (GAS) are serious human pathogens of multiple M protein strains that upregulate expression of virulence factors, including the IL-8 proteaseStreptococcus pyogenescell envelope proteinase (SpyCEP), thus blunting neutrophil-mediated killing and enabling ingress of bacteria from a superficial wound to deep tissue. We previously showed that a combination vaccine incorporating J8-DT (conserved peptide vaccine from the M protein) and a recombinant SpyCEP fragment protects against CovR/S mutants. To enhance the vaccine's safety profile, we identified a minimal epitope (S2) that was the target for anti-SpyCEP Abs that could protect IL-8 from SpyCEP-mediated proteolysis. Abs from healthy humans and from mice experimentally infected with GAS also recognized S2, albeit at low titers. Native SpyCEP may be poorly immunogenic (cryptic or subdominant), and it would be to the organism's advantage if the host did not induce a strong Ab response against it. However, S2 conjugated to diphtheria toxoid is highly immunogenic and induces Abs that recognize and neutralize SpyCEP. Hence, we describe a two-component peptide vaccine that induces Abs (anti-S2) that protect IL-8 from proteolysis and other Abs (anti-J8) that cause strain-independent killing in the presence of neutrophils. We show that either component alone is ineffectual in preventing skin infection and bacteremia due to CovR/S mutants but that the combination induces complete protection. This protection correlated with a significant influx of neutrophils to the infection site. The data strongly suggest that the lack of natural immunity to hypervirulent GAS strains in humans could be rectified by this combination vaccine.
authors.affiliation: Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, Queensland 4222, Australia; michael.good@griffith.edu.au m.pandey@griffith.edu.au.
authors.forename: Manisha
authors.initials: M
authors.lastname: Pandey
authors.affiliation: Department of Infectious Disease Immunology, Statens Serum Institut, 2300 Copenhagen, Denmark; and Department of Immunology and Microbiology, University of Copenhagen, 2200 Copenhagen, Denmark.
authors.forename: Rasmus
authors.identifier: http://orcid.org/0000-0003-0177-3032
authors.initials: R
authors.lastname: Mortensen
authors.affiliation: Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, Queensland 4222, Australia;
authors.forename: Ainslie
authors.initials: A
authors.lastname: Calcutt
authors.affiliation: Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, Queensland 4222, Australia;
authors.forename: Jessica
authors.initials: J
authors.lastname: Powell
authors.affiliation: Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, Queensland 4222, Australia;
authors.forename: Michael R
authors.initials: MR
authors.lastname: Batzloff
authors.affiliation: Department of Infectious Disease Immunology, Statens Serum Institut, 2300 Copenhagen, Denmark; and.
authors.forename: Jes
authors.initials: J
authors.lastname: Dietrich
authors.affiliation: Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, Queensland 4222, Australia; michael.good@griffith.edu.au m.pandey@griffith.edu.au.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Good
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology*; D016470:Bacteremia / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology; D002352:Carrier Proteins / Q000276:immunology*; D004168:Diphtheria Toxoid / Q000276:immunology; D005260:Female; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009504:Neutrophils / Q000276:immunology; D010447:Peptide Hydrolases / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D012867:Skin / Q000382:microbiology; D017192:Skin Diseases, Bacterial / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control; D013290:Streptococcal Infections / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control; D022541:Streptococcal Vaccines / Q000276:immunology*; D013297:Streptococcus pyogenes / Q000276:immunology* / Q000472:pathogenicity; D022223:Vaccines, Subunit / Q000276:immunology; D014614:Vaccines, Synthetic / Q000276:immunology; D037521:Virulence Factors / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004168:Diphtheria Toxoid; D022541:Streptococcal Vaccines; D022223:Vaccines, Subunit; D014614:Vaccines, Synthetic; D037521:Virulence Factors; C014689:streptococcal M protein; D010447:Peptide Hydrolases; C527349:SpyCEP protein, Streptococcus pyogenes