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

Abstract

Hypervirulent Klebsiella pneumoniae (hvKp) is an emerging threat due to its capacity to cause severe community-acquired infections and its increasing convergence with multidrug resistance. However, functional assessment of hvKp virulence still relies largely on mammalian infection models, which are costly, ethically constrained, and poorly suited for scalable early-stage screening. Here, we establish a proof-of-concept cell-based biosensing framework using the social amoeba Dictyostelium discoideum to detect capsule-associated virulence phenotypes in the model hvKp strain SGH10. Using SGH10 and a scarless capsule-null ΔwcaJ mutant, we show that loss of capsule production strongly reduces mucoviscosity, zebrafish lethality, resistance to amoebal predation, inhibition of social development, and impairment of amoebal motility. These host behavioral responses were quantified through complementary readouts, including predation plaque expansion, multicellular development, fluorescence microscopy, live-cell tracking, and exploratory multivariate integration. Compared with SGH10, the ΔwcaJ mutant produced phenotypes resembling those of the avirulent control strain KpGe, supporting capsule production as a major driver of phagocytosis resistance and host-response disruption in this model. Rather than providing a broadly validated classifier for hvKp, our results define a calibrated experimental framework in which D. discoideum functions as a living phenotypic sensor for capsule-dependent virulence traits. This platform offers a low-cost, genetically tractable, and imaging-compatible system for dissecting hvKp host interactions and for guiding future validation of scalable virulence biosensing across larger and genetically diverse K. pneumoniae collections.