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The Autotransporter BpaB Contributes to the Virulence of Burkholderia mallei in an Aerosol Model of Infection

Burkholderia mallei is a highly pathogenic bacterium that causes the zoonosis glanders. Previous studies indicated that the genome of the organism contains eight genes specifying autotransporter proteins, which are important virulence factors of Gram-negative bacteria. In the present study, we repor...

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Autores principales: Zimmerman, Shawn M., Michel, Frank, Hogan, Robert J., Lafontaine, Eric R.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4438868/
https://www.ncbi.nlm.nih.gov/pubmed/25993100
http://dx.doi.org/10.1371/journal.pone.0126437
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author Zimmerman, Shawn M.
Michel, Frank
Hogan, Robert J.
Lafontaine, Eric R.
author_facet Zimmerman, Shawn M.
Michel, Frank
Hogan, Robert J.
Lafontaine, Eric R.
author_sort Zimmerman, Shawn M.
collection PubMed
description Burkholderia mallei is a highly pathogenic bacterium that causes the zoonosis glanders. Previous studies indicated that the genome of the organism contains eight genes specifying autotransporter proteins, which are important virulence factors of Gram-negative bacteria. In the present study, we report the characterization of one of these autotransporters, BpaB. Database searches identified the bpaB gene in ten B. mallei isolates and the predicted proteins were 99-100% identical. Comparative sequence analyses indicate that the gene product is a trimeric autotransporter of 1,090 amino acids with a predicted molecular weight of 105-kDa. Consistent with this finding, we discovered that recombinant bacteria expressing bpaB produce a protein of ≥300-kDa on their surface that is reactive with a BpaB-specific monoclonal antibody. Analysis of sera from mice infected with B. mallei indicated that animals produce antibodies against BpaB during the course of disease, thus establishing production of the autotransporter in vivo. To gain insight on its role in virulence, we inactivated the bpaB gene of B. mallei strain ATCC 23344 and determined the median lethal dose of the mutant in a mouse model of aerosol infection. These experiments revealed that the bpaB mutation attenuates virulence 8-14 fold. Using a crystal violet-based assay, we also discovered that constitutive production of BpaB on the surface of B. mallei promotes biofilm formation. To our knowledge, this is the first report of a biofilm factor for this organism.
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spelling pubmed-44388682015-05-29 The Autotransporter BpaB Contributes to the Virulence of Burkholderia mallei in an Aerosol Model of Infection Zimmerman, Shawn M. Michel, Frank Hogan, Robert J. Lafontaine, Eric R. PLoS One Research Article Burkholderia mallei is a highly pathogenic bacterium that causes the zoonosis glanders. Previous studies indicated that the genome of the organism contains eight genes specifying autotransporter proteins, which are important virulence factors of Gram-negative bacteria. In the present study, we report the characterization of one of these autotransporters, BpaB. Database searches identified the bpaB gene in ten B. mallei isolates and the predicted proteins were 99-100% identical. Comparative sequence analyses indicate that the gene product is a trimeric autotransporter of 1,090 amino acids with a predicted molecular weight of 105-kDa. Consistent with this finding, we discovered that recombinant bacteria expressing bpaB produce a protein of ≥300-kDa on their surface that is reactive with a BpaB-specific monoclonal antibody. Analysis of sera from mice infected with B. mallei indicated that animals produce antibodies against BpaB during the course of disease, thus establishing production of the autotransporter in vivo. To gain insight on its role in virulence, we inactivated the bpaB gene of B. mallei strain ATCC 23344 and determined the median lethal dose of the mutant in a mouse model of aerosol infection. These experiments revealed that the bpaB mutation attenuates virulence 8-14 fold. Using a crystal violet-based assay, we also discovered that constitutive production of BpaB on the surface of B. mallei promotes biofilm formation. To our knowledge, this is the first report of a biofilm factor for this organism. Public Library of Science 2015-05-20 /pmc/articles/PMC4438868/ /pubmed/25993100 http://dx.doi.org/10.1371/journal.pone.0126437 Text en © 2015 Zimmerman et al http://creativecommons.org/licenses/by/4.0/ 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 properly credited.
spellingShingle Research Article
Zimmerman, Shawn M.
Michel, Frank
Hogan, Robert J.
Lafontaine, Eric R.
The Autotransporter BpaB Contributes to the Virulence of Burkholderia mallei in an Aerosol Model of Infection
title The Autotransporter BpaB Contributes to the Virulence of Burkholderia mallei in an Aerosol Model of Infection
title_full The Autotransporter BpaB Contributes to the Virulence of Burkholderia mallei in an Aerosol Model of Infection
title_fullStr The Autotransporter BpaB Contributes to the Virulence of Burkholderia mallei in an Aerosol Model of Infection
title_full_unstemmed The Autotransporter BpaB Contributes to the Virulence of Burkholderia mallei in an Aerosol Model of Infection
title_short The Autotransporter BpaB Contributes to the Virulence of Burkholderia mallei in an Aerosol Model of Infection
title_sort autotransporter bpab contributes to the virulence of burkholderia mallei in an aerosol model of infection
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4438868/
https://www.ncbi.nlm.nih.gov/pubmed/25993100
http://dx.doi.org/10.1371/journal.pone.0126437
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