Affiliation:
1. Department of Microbiology, University of Barcelona, Barcelona, Spain
Abstract
ABSTRACT
Some
cdt
genes are located within the genome of inducible or cryptic bacteriophages, but there is little information about the mechanisms of
cdt
transfer because of the reduced number of inducible Cdt phages described. In this study, a new self-inducible
Myoviridae
Cdt phage (ΦAA91) was isolated from a nonclinical O157:H7 Shiga toxin-producing
Escherichia coli
strain and was used to lysogenize a
cdt
-negative strain of
Shigella sonnei
. We found that the phage induced from
S. sonnei
(ΦAA91-ss) was not identical to the original phage. ΦAA91-ss was used to infect a collection of 57 bacterial strains, was infectious in 59.6% of the strains, and was able to lysogenize 22.8% of them. The complete sequence of ΦAA91-ss showed a 33,628-bp genome with characteristics of a P2-like phage with the
cdt
operon located near the
cosR
site. We found an IS
21
element composed of two open reading frames inserted within the
cox
gene of the phage, causing gene truncation. Truncation of
cox
does not affect lytic induction but could contribute to phage recombination and generation of lysogens. The IS
21
element was not present in the ΦAA91 phage from
E. coli
, but it was incorporated into the phage genome after its transduction in
Shigella
. This study shows empirically the evolution of temperate bacteriophages carrying virulence genes after infecting a new host and the generation of a phage population with better lysogenic abilities that would ultimately lead to the emergence of new pathogenic strains.
Publisher
American Society for Microbiology
Subject
Virology,Insect Science,Immunology,Microbiology
Cited by
15 articles.
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