Taxonomy
The following species are recognized: * '' Lambdavirus DE3'' * '' Lambdavirus HK629'' * '' Lambdavirus HK630'' * '' Lambdavirus lambda'' * '' Lambdavirus lvO276'' The genus also includes several unclassified viruses—including the corynephages β and ω, which infect ''Structure
Lambdaviruses areGenome
All species have been fully sequenced. They range between 42k and 49k nucleotides, with 56 to 73 proteins.Life cycle
The virus attaches to the host cell's adhesion receptors using its terminal fiber, and ejects the viral DNA into the host cytoplasm viHistory
According to ICTV's taxon history: * ''Lambda phage'' appeared in thCircumscription
The scope of the genus has changed significantly in its evolution. Originally a group of all so-called lambdoid phages (synonyms ''Lambda-like viruses'', ''Lambda-like phages'', ''Lambda phage group''), its scope has narrowed significantly. * HK022 and HK97 were abolished in 1995 but re-admitted in 2004 into this genus. In 2017 they became genus '' Hk97virus''. In 2018 HK022 was moved to '' Hendrixvirus'' by rename of the genus. In 2019 HK022 was moved to its own genus '' Shamshuipovirus''. * PA2 was abolished at an unknown date and re-admitted in 2016 in the genus '' Tl2011virus''. In 2018 it was moved to '' Oslovirus'' by rename of the genus. * phiD328 and phi80 are not found anywhere in the 2024 ICTV taxonomy. Given the above history, the latest document that defines the boundary of the genus is the 2017 document that created ''Hk97virus''. Unfortunately the document does not specifically address the inclusion criteria for ''Lambdavirus'', only the evidence for their new genus being monophyletic and reasonably similar with each other. The only part that shows the similarity among the members of ''Lambdavirus'' was in figure 2, a Gegenees BLASTN analysis using window of 100 bp and a slide of 50 bp. The lowest Gegeenes similarity among members of the group was 62.5%. The general guideline from ICTV's Bacterial and Archaeal Viruses Subcommitee in 2017 was 50% nucleotide similarity. The term ''lambdoid phage'' remains commonly used. It originally consisted of an operational definition of "phages that can recombine with lambda and form a functional, recombinant phage". The term was slightly expanded in the genomic era to mean phages that have a similar-enough functional gene order and at least some patch of homology so that, if ''hypothetically'' recombined with lambda, it would form a functional phage with all required genes. The possibility of recombination does not necessarily imply a recent common ancestor and the apparently recombinant character of P22 adds to the problem. Phages that have been called lambdoid include members as diverse as '' Lederbergvirus P22'', '' Byrnievirus HK97'', Salmonella phage ES18, Salmonella phage Gifsy-2, and '' Traversvirus tv933W''.References
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