Fogg Paul C M, Allison Heather E, Saunders Jon R, McCarthy Alan J
Microbiology Research Group, School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom.
J Virol. 2010 Jul;84(13):6876-9. doi: 10.1128/JVI.02177-09. Epub 2010 Apr 7.
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.
噬菌体λ具有一种典型的免疫机制，可防止其大肠杆菌溶原菌发生超感染。现在已知，产毒的λ样噬菌体能够以高频率发生超感染，并且我们在此证明，λ溶原菌的超感染可导致获得额外的λ基因组，这通过Southern杂交和定量PCR得到了证实。观察到多达8次整合事件，但频率非常低（6.4×10⁻⁴），并且总是在大肠杆菌中已确定的主要整合位点以多次插入的形式出现。对完整免疫区域的序列分析表明，这些多重感染的溶原菌并非免疫突变体。总之，虽然λ超感染免疫可能会受到干扰，但这是一种罕见事件。
