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Multiplication of bacteriophage P1 mutants in Shigella dysenteriae strain Sh(P1)
Abstract:
From bacteriophage P1, 10 mutants (P1cl) were isolated which are impaired in their ability to lysogenize Shigella dysenteriae Sh and which fail to make plaques when plated on Sh(P1). When Sh(P1) is infected with P1cl, a considerable proportion of the infected cells is converted into infectious centers, which eventually release P1cl but not P1. This phage release occurs over a period of several hours, during which a manyfold multiplication of infectious centers takes place. In the course of this multiplication, surviving bacteria, lysogenic for P1 only, are produced by segregation. At high multiplicity of infection, Sh(P1) are killed without producing any phage.
Insights
Ten bacteriophage P1 mutants (P1cl) showed impaired lysogenization of Shigella dysenteriae Sh. These mutants released P1cl phage but not wild-type P1, indicating altered phage replication cycles.
Area of Science:
- Microbiology
- Virology
- Bacteriophage Research
Background:
- Bacteriophage P1 is a well-studied model organism.
- Lysogenization is a key phage life cycle step.
- Shigella dysenteriae is a significant human pathogen.
Purpose of the Study:
- To characterize P1cl mutants with altered lysogenization and plaque formation on Shigella.
- To investigate the phage release mechanism of P1cl in Shigella.
Main Methods:
- Isolation and characterization of bacteriophage P1 mutants (P1cl).
- Infection assays of Shigella dysenteriae Sh and Sh(P1) with P1cl.
- Monitoring of phage release and bacterial survival.
Main Results:
- P1cl mutants were impaired in lysogenizing Shigella dysenteriae Sh and plaque formation on Sh(P1).
- Infection of Sh(P1) with P1cl resulted in infectious centers releasing P1cl, not P1.
- Bacterial segregation produced P1-lysogenic survivors during phage multiplication.
- High multiplicity infection led to bacterial death without phage production.
Conclusions:
- P1cl mutants exhibit defects in lysogenization and alter phage release pathways.
- The observed phage release suggests a modified replication or assembly process in P1cl-infected cells.
- Segregation of lysogenic bacteria indicates a complex interaction between phage mutants and host cells.