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Updated: Mar 28, 2026
Genetic Engineering of Dictyostelium discoideum Cells Based on Selection and Growth on Bacteria
Published on: January 25, 2019
Dissection of Francisella-Host Cell Interactions in Dictyostelium discoideum
Elisabeth O Lampe1,2, Yannick Brenz3, Lydia Herrmann3
1Centre for Integrative Microbial Evolution (CIME), University of Oslo, Oslo, Norway.
Abstract:
Francisella bacteria cause severe disease in both vertebrates and invertebrates and include one of the most infectious human pathogens. Mammalian cell lines have mainly been used to study the mechanisms by which Francisella manipulates its host to replicate within a large variety of hosts and cell types, including macrophages. Here, we describe the establishment of a genetically and biochemically tractable infection model: the amoeba Dictyostelium discoideum combined with the fish pathogen Francisella noatunensis subsp. noatunensis. Phagocytosed F. noatunensis subsp. noatunensis interacts with the endosomal pathway and escapes further phagosomal maturation by translocating into the host cell cytosol. F. noatunensis subsp. noatunensis lacking IglC, a known virulence determinant required for Francisella intracellular replication, follows the normal phagosomal maturation and does not grow in Dictyostelium. The attenuation of the F. noatunensis subsp. noatunensis ΔiglC mutant was confirmed in a zebrafish embryo model, where growth of F. noatunensis subsp. noatunensis ΔiglC was restricted. In Dictyostelium, F. noatunensis subsp. noatunensis interacts with the autophagic machinery. The intracellular bacteria colocalize with autophagic markers, and when autophagy is impaired (Dictyostelium Δatg1), F. noatunensis subsp. noatunensis accumulates within Dictyostelium cells. Altogether, the Dictyostelium-F. noatunensis subsp. noatunensis infection model recapitulates the course of infection described in other host systems. The genetic and biochemical tractability of the system allows new approaches to elucidate the dynamic interactions between pathogenic Francisella and its host organism.
Insights
A new Dictyostelium discoideum infection model using Francisella noatunensis reveals bacterial evasion of host defenses. This model helps understand Francisella pathogenesis and host-pathogen interactions.
Area of Science:
- Microbiology
- Cell Biology
- Infectious Diseases
Background:
- Francisella bacteria are highly infectious pathogens causing severe diseases in various hosts.
- Mammalian cell lines are primarily used to study Francisella host manipulation mechanisms.
- Understanding Francisella pathogenesis requires tractable models for host-pathogen interaction studies.
Purpose of the Study:
- To establish and characterize a novel Dictyostelium discoideum-Francisella noatunensis infection model.
- To investigate Francisella intracellular replication and host cell interactions using this model.
- To explore the role of bacterial virulence factors and host autophagy in Francisella infection.
Main Methods:
- Infection of Dictyostelium discoideum with Francisella noatunensis subsp. noatunensis.
- Analysis of bacterial intracellular trafficking and phagosomal escape.
- Assessment of bacterial growth and virulence using wild-type and mutant strains (ΔiglC).
- Confirmation of bacterial attenuation in a zebrafish embryo model.
- Investigation of bacterial interactions with the host autophagic pathway.
Main Results:
- Francisella noatunensis subsp. noatunensis translocates into the Dictyostelium cytosol, evading phagosomal maturation.
- A Francisella mutant lacking the virulence determinant IglC is attenuated and does not replicate in Dictyostelium.
- Bacterial attenuation of the ΔiglC mutant is confirmed in zebrafish embryos.
- Francisella noatunensis subsp. noatunensis interacts with Dictyostelium autophagy, accumulating when autophagy is impaired.
- The Dictyostelium model recapitulates key aspects of Francisella infection observed in other systems.
Conclusions:
- The Dictyostelium-Francisella noatunensis model provides a genetically tractable system to study bacterial pathogenesis.
- This model elucidates Francisella's strategies for host cell invasion and survival.
- It offers new avenues for dissecting the dynamic interplay between Francisella and its hosts.
