103), including 420 copies of the major capsid protein (Mr 55 103).
|
Type Species |
(P22) |
Virions base plates have 6 prominent spikes. DNA is circularly permuted, terminally redundant, and packaged from a pac site by a headful mechanism. The genetic map is circular.
Virions have icosahedral heads with 72 faintly visible capsomers (60 hexamers, 12 pentamers; T = 7) and are 60-65 nm in diameter. Tails are 18 nm long and provided with a base plate with 6 spikes.
Physicochemical and Physical Properties
Virion buoyant density in CsC1 is 1.51 g/cm3; S20w is 500S. Infectivity is ether- and chloroform-resistant.
Genomes are 43-44 kbp in size, correspond to about 50% of particle weight, and a G+C content of 47%.
Virions contain 8-9 structural proteins (Mr 18?-94 103), including 420 copies of the major capsid protein (Mr 55 103).
Not known.
Not known.
Genome Organization and Replication
The genetic map is circularly permuted, has terminal repeats of about 1700 bp (2% of the genome), and comprises at least 36 genes. The Enterobacteria phage P22 (P22) genome is partially (13.5%) homologous to 
DNA. Common sequences are limited to control-immunity, DNA synthesis, lysis, and integration regions. The integration system is dispensable. Transcription starts with regulatory genes and proceeds in three partly overlapping waves. Replication starts at a single site, is unidirectional, and involves the formation of 
structures and a rolling-circle mechanism. Progeny DNA is cut from concatemers at a pac site and packaged by a headful mechanism.
No group antigens are reported.
Phages are temperate and general transductants with converting ability. They infect Salmonella (and possibly Proteus) bacteria, and have under suitable conditions very high (up to 1000) burst sizes. Similar phages are found in other Gram-negative bacteria. Prophages integrate at several specific sites in the bacterial genome and are UV-inducible.
List of Species Demarcation Criteria in the Genus
Not applicable.
Official virus species names are in italics. Tentative virus species names, alternative names ( ), strains or serotypes are not italicized. Virus names and assigned abbreviations ( ) are:
|
Enterobacteria phage P22 |
(P22) |
Tentative Species in the Genus
|
Aeromonas phage Aa-1 |
(Aa-1) |
|
Azotobacter phage A12 |
(A12) |
|
Enterobacteria phage L |
(L) |
|
Enterobacteria phage LP7 |
(LP7) |
|
Enterobacteria phage Mg40 |
(Mg40) |
|
Enterobacteria phage PSA78 |
(PSA78) |
|
Enterobacteria phage Sf6 |
(Sf6) |
|
Hyphomicrobium phage Hy30 |
(Hy30) |
|
Pseudomonas phage 525 |
(525) |
|
Vibrio phage O6N-72P |
(06N-72P) |
-like viruses (see Genome Organization.
|
|  |