Characterization of pathogenesis of and immune response to Burkholderia pseudomallei K96243 using both inhalational and intraperitoneal infection models in BALB/c and C57BL/6 mice

PLoS One. 2017 Feb 24;12(2):e0172627. doi: 10.1371/journal.pone.0172627. eCollection 2017.

Abstract

Burkholderia pseudomallei, the etiologic agent of melioidosis, is a Gram negative bacterium designated as a Tier 1 threat. This bacterium is known to be endemic in Southeast Asia and Northern Australia and can infect humans and animals by several routes. Inhalational melioidosis has been associated with monsoonal rains in endemic areas and is also a significant concern in the biodefense community. There are currently no effective vaccines for B. pseudomallei and antibiotic treatment can be hampered by non-specific symptomology and also the high rate of naturally occurring antibiotic resistant strains. Well-characterized animal models will be essential when selecting novel medical countermeasures for evaluation prior to human clinical trials. Here, we further characterize differences between the responses of BALB/c and C57BL/6 mice when challenged with low doses of a low-passage and well-defined stock of B. pseudomallei K96243 via either intraperitoneal or aerosol routes of exposure. Before challenge, mice were implanted with a transponder to collect body temperature readings, and daily body weights were also recorded. Mice were euthanized on select days for pathological analyses and determination of the bacterial burden in selected tissues (blood, lungs, liver, and spleen). Additionally, spleen homogenate and sera samples were analyzed to better characterize the host immune response after infection with aerosolized bacteria. These clinical, pathological, and immunological data highlighted and confirmed important similarities and differences between these murine models and exposure routes.

MeSH terms

  • Administration, Inhalation
  • Animals
  • Bacterial Load
  • Body Temperature
  • Body Weight
  • Burkholderia pseudomallei / growth & development
  • Burkholderia pseudomallei / immunology*
  • Burkholderia pseudomallei / pathogenicity
  • Colony Count, Microbial
  • Cytokines / biosynthesis
  • Cytokines / immunology
  • Disease Models, Animal
  • Female
  • Granulocytes / immunology
  • Granulocytes / microbiology
  • Humans
  • Immunity, Innate*
  • Injections, Intraperitoneal
  • Liver / immunology*
  • Liver / microbiology
  • Lung / immunology*
  • Lung / microbiology
  • Lymphocyte Subsets / classification
  • Lymphocyte Subsets / immunology
  • Lymphocyte Subsets / microbiology
  • Melioidosis / immunology*
  • Melioidosis / microbiology
  • Melioidosis / pathology
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Monocytes / immunology
  • Monocytes / microbiology
  • Species Specificity
  • Spleen / immunology*
  • Spleen / microbiology

Substances

  • Cytokines

Grants and funding

This research was funded by the Medical Biological Defense Research Program; Defense Threat Reduction Agency (DTRA) (CB3846 PPE-1 Burkholderia) (www.dtra.mil). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.