title: Bacteriophage lambda: a paradigm revisited.
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 x 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.
authors.affiliation: Microbiology Research Group, School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom.
authors.forename: Paul C M
authors.initials: PC
authors.lastname: Fogg
authors.forename: Heather E
authors.initials: HE
authors.lastname: Allison
authors.forename: Jon R
authors.initials: JR
authors.lastname: Saunders
authors.forename: Alan J
authors.initials: AJ
authors.lastname: McCarthy
mesh_terms: D000595:Amino Acid Sequence; D010582:Bacteriophage lambda / Q000254:growth & development / Q000502:physiology*; D001483:Base Sequence; D015139:Blotting, Southern; D004269:DNA, Bacterial / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics; D004926:Escherichia coli / Q000821:virology*; D008242:Lysogeny / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D039002:Prophages / Q000254:growth & development / Q000502:physiology*; D017422:Sequence Analysis, DNA; D015163:Superinfection; D016662:Virus Integration
chemical_list: D004269:DNA, Bacterial; D004279:DNA, Viral