DESCRIPTION OF VIRUSES

Family Siphoviridae

Genus “C2-like Viruses“

Genus “C2-like Viruses“

Type Species

Lactococcus phage c2

(c2)

Distinguishing Features

Heads are prolate; phage DNA has cos sites and codes for a putative type B DNA polymerase.

Virion Properties

Morphology

Virions have prolate heads of about 56 41  nm and tails of 98 9  nm provided with a collar (inconstant) and a small base plate, and produce rare morphological aberrations (two heads joined by a bridge).

Physicochemical and Physical Properties

Virion buoyant density in CsC1 is 1.46  g/cm3.

Nucleic Acid

Genomes are about 22  kbp in size (22,163-22,195  bp) and have a G+C content of about 36 (35-40)%. The genomes of Lactococcus phage c2 (c2) and Lactococcus phage bIL67 (bIL67) have been fully sequenced.

Proteins

Virions have at least 6 structural proteins (Mr 19.2-175 103); major proteins are of 29, 90, and 175 103. Type B (E. coli Pol II) DNA polymerase is apparently encoded. Amino acid sequences for c2 and bIL67 are available at GenBank and EMBL.

Lipids

Not known.

Carbohydrates

Not known.

Genome Organization and Replication

The genetic map is linear. The genome includes 37-38 genes in two clusters and has cohesive ends. Early and late genes are separated by an intergenic region. Late genes are transcribed leftward.

Biological Properties

Phages are temperate and specific for lactococci.

List of Species Demarcation Criteria in the Genus

Not applicable.

List of Species in the Genus

Official virus species names are in italics. Tentative virus species names, alternative names ( ), strains or serotypes are not italicized. Virus names, genome sequence accession numbers [ ], and assigned abbreviations ( ) are:

Species in the Genus

Lactococcus phage c2

[L48605]

(c2)

Lactococcus phage bIL67

[L33769]

(bIL67)

Tentative Species in the Genus

Lactococcus phage c6A

(PBc6A)

Lactococcus phage P001

(P001)

Lactococcus phage vML3

(vML3)

(Lactococcus phage ML3)

(ML3)

(Lactococcus phage ml3)

(ml3)

(Lactococcus phage 3ML)

(3ML)

About 200 additional, poorly characterized lactococcal phages have been reported that are morphologically identical to c2.


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