Combinatorial Synthetic Peptide Vaccine Strategy Protects against Hypervirulent CovR/S Mutant Streptococci.
J Immunol
; 196(8): 3364-74, 2016 Apr 15.
Article
em En
| MEDLINE
| ID: mdl-26969753
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.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Peptídeo Hidrolases
/
Infecções Estreptocócicas
/
Streptococcus pyogenes
/
Proteínas da Membrana Bacteriana Externa
/
Proteínas de Transporte
/
Vacinas Estreptocócicas
/
Antígenos de Bactérias
Tipo de estudo:
Prognostic_studies
Limite:
Animals
/
Female
/
Humans
Idioma:
En
Ano de publicação:
2016
Tipo de documento:
Article