Galleria mellonella as an Infection Model for Bacillus anthracis Sterne

Area of Science:

• Microbiology
• Infectious Diseases
• Toxicology

Background:

• Bacterial virulence determinants are crucial for understanding infection and identifying drug targets.
• Traditional animal models, like mice, face ethical and logistical constraints.
• The greater wax moth larva, Galleria mellonella, is emerging as an alternative invertebrate infection model.

Purpose of the Study:

• To establish Galleria mellonella as a viable infection model for Bacillus anthracis Sterne.
• To validate infection assays in G. mellonella for assessing B. anthracis virulence.
• To evaluate G. mellonella's utility in identifying novel virulence factors of B. anthracis.

Main Methods:

• Development and validation of survival and competition assays in G. mellonella for B. anthracis Sterne.
• Testing transposon mutants with known in vitro phenotypes (hydrogen peroxide susceptibility) in the G. mellonella model.
• Genetic and phenotypic characterization of a B. anthracis mutant exhibiting reduced virulence in G. mellonella.

Main Results:

• G. mellonella infection assays successfully validated known B. anthracis virulence genes.
• A B. anthracis transposon mutant with increased in vitro hydrogen peroxide susceptibility showed decreased virulence in G. mellonella.
• This attenuated mutant was identified to have a disruption in the petrobactin biosynthesis operon (asbABCDEF).

Conclusions:

• Galleria mellonella can accurately detect attenuated virulence of Bacillus anthracis Sterne.
• The G. mellonella model is consistent with findings from mammalian infection models.
• G. mellonella serves as a practical and ethical alternative to vertebrate testing for early-stage virulence gene assessment.