The lipopolysaccharide core of Brucella abortus acts as a shield against innate immunity recognition

Date

2012

Authors

Conde Álvarez, Raquel
Bargen, Kristine von
Grilló Dolset, María Jesús
Jerala, Roman
Brandenburg, Klaus
Llobet, Enrique
Bengoechea Alonso, José Antonio
Moreno, Edgardo
Moriyón Uría, Ignacio
Gorvel, Jean-Pierre

Director

Publisher

Public Library of Science
Acceso abierto / Sarbide irekia
Artículo / Artikulua
Versión publicada / Argitaratu den bertsioa

Project identifier

  • European Commission/FP7/221948/ openaire
  • MICINN//AGL2008-04514-C03-01/ES/ recolecta
  • MICINN//SAF2009-07885/ES/ recolecta
  • MICINN//AGL2010-20247/ES/ recolecta
Impacto

Abstract

Innate immunity recognizes bacterial molecules bearing pathogen-associated molecular patterns to launch inflammatory responses leading to the activation of adaptive immunity. However, the lipopolysaccharide (LPS) of the gram-negative bacterium Brucella lacks a marked pathogen-associated molecular pattern, and it has been postulated that this delays the development of immunity, creating a gap that is critical for the bacterium to reach the intracellular replicative niche. We found that a B. abortus mutant in the wadC gene displayed a disrupted LPS core while keeping both the LPS O-polysaccharide and lipid A. In mice, the wadC mutant induced proinflammatory responses and was attenuated. In addition, it was sensitive to killing by non-immune serum and bactericidal peptides and did not multiply in dendritic cells being targeted to lysosomal compartments. In contrast to wild type B. abortus, the wadC mutant induced dendritic cell maturation and secretion of pro-inflammatory cytokines. All these properties were reproduced by the wadC mutant purified LPS in a TLR4-dependent manner. Moreover, the core-mutated LPS displayed an increased binding to MD-2, the TLR4 co-receptor leading to subsequent increase in intracellular signaling. Here we show that Brucella escapes recognition in early stages of infection by expressing a shield against recognition by innate immunity in its LPS core and identify a novel virulence mechanism in intracellular pathogenic gram-negative bacteria. These results also encourage for an improvement in the generation of novel bacterial vaccines.

Description

Keywords

Rough vaccines, Mutants, O-polysaccharide, Parasitology, Virology, Virulence, Dendritic cell, Maturation, Cationic peptides, Lipid-A, Gene, Microbiology, Cutting edge, Polysaccharide synthesis

Department

IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua

Faculty/School

Degree

Doctorate program

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© 2012 Conde-Álvarez et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Licencia

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