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Infect Immun. 2017 May 23;85(6). pii: e00937-16. doi: 10.1128/IAI.00937-16. Print 2017 Jun.

Cyclic AMP-Elevating Capacity of Adenylate Cyclase Toxin-Hemolysin Is Sufficient for Lung Infection but Not for Full Virulence of Bordetella pertussis.

Author information

1
Institute of Microbiology of the CAS, v.v.i., Prague, Czech Republic.
2
Czech Centre for Phenogenomics, Division BIOCEV, Institute of Molecular Genetics of the CAS, v.v.i., Czech Academy of Sciences, Prague, Czech Republic.
3
Institut Pasteur, Molecular Prevention and Therapy of Human Diseases Unit, Paris, France.
4
Centre National de la Recherche Scientifique (CNRS), URA3012, Paris, France.
5
Institute of Microbiology of the CAS, v.v.i., Prague, Czech Republic sebo@biomed.cas.cz.

Abstract

The adenylate cyclase toxin-hemolysin (CyaA, ACT, or AC-Hly) of Bordetella pertussis targets phagocytic cells expressing the complement receptor 3 (CR3, Mac-1, αMβ2 integrin, or CD11b/CD18). CyaA delivers into cells an N-terminal adenylyl cyclase (AC) enzyme domain that is activated by cytosolic calmodulin and catalyzes unregulated conversion of cellular ATP into cyclic AMP (cAMP), a key second messenger subverting bactericidal activities of phagocytes. In parallel, the hemolysin (Hly) moiety of CyaA forms cation-selective hemolytic pores that permeabilize target cell membranes. We constructed the first B. pertussis mutant secreting a CyaA toxin having an intact capacity to deliver the AC enzyme into CD11b-expressing (CD11b+) host phagocytes but impaired in formation of cell-permeabilizing pores and defective in cAMP elevation in CD11b- cells. The nonhemolytic AC+ Hly- bacteria inhibited the antigen-presenting capacities of coincubated mouse dendritic cells in vitro and skewed their Toll-like receptor (TLR)-triggered maturation toward a tolerogenic phenotype. The AC+ Hly- mutant also infected mouse lungs as efficiently as the parental AC+ Hly+ strain. Hence, elevation of cAMP in CD11b- cells and/or the pore-forming capacity of CyaA were not required for infection of mouse airways. The latter activities were, however, involved in bacterial penetration across the epithelial layer, enhanced neutrophil influx into lung parenchyma during sublethal infections, and the exacerbated lung pathology and lethality of B. pertussis infections at higher inoculation doses (>107 CFU/mouse). The pore-forming activity of CyaA further synergized with the cAMP-elevating activity in downregulation of major histocompatibility complex class II (MHC-II) molecules on infiltrating myeloid cells, likely contributing to immune subversion of host defenses by the whooping cough agent.

KEYWORDS:

Bordetella pertussis; adenylate cyclase toxin-hemolysin; cAMP intoxication; lung colonization; pore-forming activity; virulence

PMID:
28396322
PMCID:
PMC5442630
DOI:
10.1128/IAI.00937-16
[Indexed for MEDLINE]
Free PMC Article

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