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Updated: Oct 29, 2025
Using a Bacterial Pathogen to Probe for Cellular and Organismic-level Host Responses
Published on: February 22, 2019
The Genomics and Cell Biology of Host-Beneficial Intracellular Infections
1Biodesign Center for Mechanisms of Evolution, School of Life Sciences, Arizona State University, Tempe, Arizona 85287, USA;
Abstract:
Microbes gain access to eukaryotic cells as food for bacteria-grazing protists, for host protection by microbe-killing immune cells, or for microbial benefit when pathogens enter host cells to replicate. But microbes can also gain access to a host cell and become an important-often required-beneficial partner. The oldest beneficial microbial infections are the ancient eukaryotic organelles now called the mitochondrion and plastid. But numerous other host-beneficial intracellular infections occur throughout eukaryotes. Here I review the genomics and cell biology of these interactions with a focus on intracellular bacteria. The genomes of host-beneficial intracellular bacteria have features that span a previously unfilled gap between pathogens and organelles. Host cell adaptations to allow the intracellular persistence of beneficial bacteria are found along with evidence for the microbial manipulation of host cells, but the cellular mechanisms of beneficial bacterial infections are not well understood.
Insights
Microbes can be beneficial intracellular partners, not just pathogens or food. Their genomes and host cell adaptations reveal unique infection strategies, though mechanisms remain unclear.
Area of Science:
- Microbiology
- Cell Biology
- Genomics
Background:
- Microbes enter eukaryotic cells for various reasons, including nutrition, host defense, or pathogen replication.
- Some intracellular microbes evolve into essential, beneficial partners, akin to ancient organelles like mitochondria.
- Numerous beneficial intracellular microbial infections exist across eukaryotes.
Purpose of the Study:
- To review the genomics and cell biology of host-beneficial intracellular bacterial interactions.
- To explore the unique genomic features of beneficial intracellular bacteria.
- To understand host cell adaptations and microbial manipulation in these symbiotic relationships.
Main Methods:
- Genomic analysis of host-beneficial intracellular bacteria.
- Review of cell biology studies on intracellular microbial infections.
- Comparative analysis of bacterial genomes (pathogens, organelles, beneficial symbionts).
Main Results:
- Genomes of beneficial intracellular bacteria exhibit distinct features, bridging the gap between pathogens and organelles.
- Host cells show adaptations supporting the intracellular persistence of beneficial bacteria.
- Evidence suggests beneficial microbes manipulate host cells for their own benefit.
Conclusions:
- Host-beneficial intracellular bacterial infections represent a significant biological phenomenon.
- Genomic and cellular studies highlight unique adaptations in these symbiotic relationships.
- Further research is needed to elucidate the precise cellular mechanisms of beneficial bacterial infections.
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