Characterization of the Burkholderia mallei tonB Mutant and Its Potential as a Backbone Strain for Vaccine Development

PLoS Negl Trop Dis. 2015 Jun 26;9(6):e0003863. doi: 10.1371/journal.pntd.0003863. eCollection 2015.

Abstract

Background: In this study, a Burkholderia mallei tonB mutant (TMM001) deficient in iron acquisition was constructed, characterized, and evaluated for its protective properties in acute inhalational infection models of murine glanders and melioidosis.

Methodology/principal findings: Compared to the wild-type, TMM001 exhibits slower growth kinetics, siderophore hyper-secretion and the inability to utilize heme-containing proteins as iron sources. A series of animal challenge studies showed an inverse correlation between the percentage of survival in BALB/c mice and iron-dependent TMM001 growth. Upon evaluation of TMM001 as a potential protective strain against infection, we found 100% survival following B. mallei CSM001 challenge of mice previously receiving 1.5 x 10(4) CFU of TMM001. At 21 days post-immunization, TMM001-treated animals showed significantly higher levels of B. mallei-specific IgG1, IgG2a and IgM when compared to PBS-treated controls. At 48 h post-challenge, PBS-treated controls exhibited higher levels of serum inflammatory cytokines and more severe pathological damage to target organs compared to animals receiving TMM001. In a cross-protection study of acute inhalational melioidosis with B. pseudomallei, TMM001-treated mice were significantly protected. While wild type was cleared in all B. mallei challenge studies, mice failed to clear TMM001.

Conclusions/significance: Although further work is needed to prevent chronic infection by TMM001 while maintaining immunogenicity, our attenuated strain demonstrates great potential as a backbone strain for future vaccine development against both glanders and melioidosis.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Bacterial Proteins / genetics*
  • Bacterial Vaccines / genetics*
  • Burkholderia mallei / genetics*
  • Burkholderia mallei / immunology
  • Burkholderia mallei / metabolism
  • Cloning, Molecular
  • DNA Primers / genetics
  • Drug Discovery / methods
  • Female
  • Glanders / prevention & control*
  • Iron / metabolism
  • Melioidosis / prevention & control*
  • Membrane Proteins / genetics*
  • Mice
  • Mice, Inbred BALB C
  • Plasmids / genetics
  • Survival Analysis

Substances

  • Bacterial Proteins
  • Bacterial Vaccines
  • DNA Primers
  • Membrane Proteins
  • tonB protein, Bacteria
  • Iron