A Dictyostelium discoideum Cell-Based Biosensor Reveals Capsule-Associated Virulence Phenotypes in Hypervirulent...

Area of Science:

• Microbiology and Microbial Pathogenesis
• Host-Pathogen Interactions
• Biosensing and Novel Assays

Background:

• Hypervirulent Klebsiella pneumoniae (hvKp) poses a significant threat due to severe infections and rising multidrug resistance.
• Current methods for assessing hvKp virulence, primarily mammalian models, are expensive, ethically challenging, and not scalable for early screening.
• There is a need for alternative, efficient, and cost-effective methods to evaluate hvKp virulence factors.

Purpose of the Study:

• To establish a proof-of-concept cell-based biosensing framework using Dictyostelium discoideum for detecting capsule-associated virulence phenotypes in hvKp.
• To evaluate the utility of D. discoideum as a living sensor for hvKp virulence traits, specifically focusing on capsule production.
• To provide a low-cost, scalable platform for dissecting hvKp host interactions and guiding future virulence biosensing development.

Main Methods:

• Utilized the social amoeba Dictyostelium discoideum as a biosensing platform.
• Compared the model hvKp strain SGH10 with a scarless capsule-null mutant (ΔwcaJ) and an avirulent control strain (KpGe).
• Quantified host behavioral responses and virulence phenotypes using predation plaque assays, multicellular development, fluorescence microscopy, live-cell tracking, and multivariate integration.

Main Results:

• Loss of capsule production in the ΔwcaJ mutant significantly reduced mucoviscosity, zebrafish lethality, resistance to amoebal predation, and inhibited social development.
• The ΔwcaJ mutant exhibited phenotypes similar to the avirulent control strain KpGe, highlighting capsule as a key driver of phagocytosis resistance and host-response disruption.
• The D. discoideum framework successfully differentiated between capsule-producing and non-producing hvKp strains, demonstrating its potential as a phenotypic sensor.

Conclusions:

• Dictyostelium discoideum serves as a viable living phenotypic sensor for detecting capsule-dependent virulence traits in hypervirulent Klebsiella pneumoniae.
• This cell-based biosensing platform offers a low-cost, genetically tractable, and imaging-compatible alternative to traditional mammalian models for hvKp virulence assessment.
• The established framework provides a foundation for dissecting hvKp-host interactions and advancing scalable virulence biosensing for diverse K. pneumoniae collections.