Vaccine. 2016 Nov 10. pii: S0264-410X(16)31018-0. doi: 10.1016/j.vaccine.2016.11.001. [Epub ahead of print]

Immunization with LytB protein of Streptococcus pneumoniae activates complement-mediated phagocytosis and induces protection against pneumonia and sepsis.

Corsini B1, Aguinagalde L1, Ruiz S2, Domenech M2, Antequera ML1, Fenoll A1, García P2, García E2, Yuste J3.

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Abstract

The cell wall glucosaminidase LytB of Streptococcus pneumoniae is a surface exposed protein involved in daughter cell separation, biofilm formation and contributes to different aspects of the pathogenesis process. In this study we have characterized the antibody responses after immunization of mice with LytB in the presence of alhydrogel as an adjuvant. Enzyme-linked immunosorbent assays measuring different subclasses of immunoglobulin G, demonstrated that the antibody responses to LytB were predominantly IgG1 and IgG2b, followed by IgG3 and IgG2a subclasses. Complement-mediated immunity against two different pneumococcal serotypes was investigated using sera from immunized mice. Immunization with LytB increased the recognition of S. pneumoniae by complement components C1q and C3b demonstrating that anti-LytB antibodies trigger activation of the classical pathway. Phagocytosis assays showed that serum containing antibodies to LytB stimulates neutrophil-mediated phagocytosis against S. pneumoniae. Animal models of infection including invasive pneumonia and sepsis were performed with two different clinical isolates. Vaccination with LytB increased bacterial clearance and induced protection demonstrating that LytB might be a good candidate to be considered in a future protein-based vaccine against S. pneumoniae.

Copyright © 2016 Elsevier Ltd. All rights reserved.

KEYWORDS:

Cell wall hydrolase; Complement immunity; LytB; Phagocytosis; Streptococcus pneumoniae; Vaccine protein

PMID: 27840016 DOI: 10.1016/j.vaccine.2016.11.001

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