Bacteriophage Lambda: a Paradigm Revisited

• DOI: 10.1128/jvi.02177-09
• Publication Date: 2010-04-08T01:10:20Z
• Authors: Paul C. M. Fogg; Heather E. Allison; Jon R. Saunders; Alan J. McCarthy
• Keywords: DNA, Bacterial; 0303 health sciences; Base Sequence; Prophages; Virus Integration; Molecular Sequence Data; Sequence Analysis, DNA; Bacteriophage lambda; Polymerase Chain Reaction; 3. Good health; Blotting, Southern; 03 medical and health sciences; Superinfection; DNA, Viral; Escherichia coli; Amino Acid Sequence; Lysogeny

ABSTRACT

Bacteriophage lambda has an archetypal immunity system, which prevents the superinfection of its Escherichia coli lysogens. It is now known that superinfection can occur with toxigenic lambda-like phages at a high frequency, and here we demonstrate that the superinfection of a lambda lysogen can lead to the acquisition of additional lambda genomes, which was confirmed by Southern hybridization and quantitative PCR. As many as eight integration events were observed but at a very low frequency (6.4 × 10 −4 ) and always as multiple insertions at the established primary integration site in E. coli . Sequence analysis of the complete immunity region demonstrated that these multiply infected lysogens were not immunity mutants. In conclusion, although lambda superinfection immunity can be confounded, it is a rare event.