Episode Summary

A bacteriophage that overcomes the bacterial CRISPR/Cas immune system by interrupting the CRISPR DNA with its own genome

Microbe of the episode:

Wenzhou mammarenavirus

Jesse's takeaways

Bacteria have many ways to resist being exploited by bacteriophage viruses, including the adaptable CRISPR/Cas system that uses a piece of viral nucleic acid sequence to target and destroy incoming phages. But phages also have many ways to evade and disrupt bacterial defenses.

In this study, a phage is discovered that inserts its own genome into the CRISPR/Cas sequence in the bacterial genome, disrupting the bacterial defenses. To escape the defenses while it is doing this insertion, it carries genes for previously-unknown anti-CRISPR proteins. But inserting and removing a viral sequence from the bacterial genome is not always a clean procedure.

Journal Paper

Varble A, Campisi E, Euler CW, Maguin P, Kozlova A, Fyodorova J, Rostøl JT, Fischetti VA, Marraffini LA. 2021. Prophage integration into CRISPR loci enables evasion of antiviral immunity in Streptococcus pyogenes. 12. Nat Microbiol 6:1516–1525.

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Shigella phage A1-1. By Kortright