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Updated: Sep 13, 2025

Phage Phenomics: Physiological Approaches to Characterize Novel Viral Proteins
09:40

Phage Phenomics: Physiological Approaches to Characterize Novel Viral Proteins

Published on: June 11, 2015

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The prototypic crAssphage is a linear phage-plasmid

Danica T Schmidtke1, Angela S Hickey2, Jakob Wirbel3

  • 1Department of Microbiology and Immunology, Stanford University, Stanford, CA, USA.

Cell Host & Microbe
|July 29, 2025
PubMed

Insights

The human gut virus crAssphage (Caudovirales) exists as a phage-plasmid, persisting extrachromosomally without lysis. This study reveals its broad host range and potential for dual lifestyles, explaining its abundance in gut microbiomes.

Area of Science:

  • Microbiology
  • Virology
  • Human Gut Microbiome Research

Background:

  • The crAssphage (Caudovirales), a ubiquitous human gut virus, is poorly understood due to its uncultured nature.
  • Its non-lytic behavior suggests an atypical lifestyle, distinct from typical bacteriophages.

Purpose of the Study:

  • To characterize the lifestyle and host interactions of the prototypic crAssphage (Caudovirales).
  • To investigate the replication and persistence mechanisms of crAssphage within prevalent gut bacteria.

Main Methods:

  • Utilized a plaque-free culturing technique to study crAssphage replication.
  • Analyzed phage-plasmid gene transcription and potential replication origins.
  • Determined host range on key gut bacteria, including Phocaeicola and Bacteroides species.

Main Results:

  • Demonstrated that crAssphage exists as a linear phage-plasmid, maintaining extrachromosomal persistence.
  • Identified transcription of phage and plasmid genes, indicating active replication.
  • Revealed a broad host range, with successful replication in Phocaeicola vulgatus, P. dorei, and Bacteroides stercoris without significant lysis.

Conclusions:

  • CrAssphage exhibits a unique dual lifestyle, functioning as both a phage and a plasmid.
  • Its ability to replicate extrachromosomally and persist across diverse hosts contributes to its prevalence in the human gut microbiome.
Keywords:
BacteroidotaCarjivirus communisPhocaeicolabacteriophagecrAssphagemicrobial genomicsmicrobiomephage culturingphage-plasmidplasmid

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