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Virus classification
Group: Group I (dsDNA)
Family: Corticoviridae
Genus: Corticovirus
Type Species
  • Pseudoalteromonas phage PM2

Corticovirus is a genus of viruses, in the family Corticoviridae. Bacteria serve as natural hosts. There is currently only one species in this genus: the type species Pseudoalteromonas phage PM2.[1][2] The name is derived from Latin cortex, corticis (meaning 'crust' or 'bark'). However, prophages closely related to PM2 are abundant in the genomes of aquatic bacteria, suggesting that the ecological importance of corticoviruses might be underestimated.[3] The whole family (Corticoviridae) has been little-studied.


Group: dsDNA



The virons consist of a round, icosahedral, non-enveloped capsid of a diameter of 60 nm and an internal lipid membrane located between outer and inner protein shell.[4] The shells are composed of three layers whose surfaces reveals a pattern with distinctive features,[5] including bush-like spikes protruding from the twelve vertices.[6]

The icosahedral capsid (T = 21) is 56 nanometers (nm) in diameter and is composed of 1200 P1 (spike) and 60 P2 (capsid) proteins. The pentameric receptor-binding spikes protrude from the 12 fivefold axes. The capsid encloses an internal lipid core containing the structural proteins P3 to P10.


The genome is not segmented, constitutes 13% of the virus's weight and contains a single molecule of circular, supercoiled, double-stranded DNA of 9.5-12 kilobases in length. The genome has a g + c content of 43%.[7] It encodes ~21 proteins.

Transcription is organised into three operons.

Replication of the genome is via a rolling-circle mechanism.

Genus Structure Symmetry Capsid Genomic Arrangement Genomic Segmentation
Corticovirus Polyhedral T=21 Non-Enveloped Circular Monopartite

Life Cycle[edit]

Viral replication is cytoplasmic. Entry into the host cell is achieved by adsorption into the host cell. DNA-templated transcription is the method of transcription. Bacteria serve as the natural host. Transmission routes are passive diffusion.[1]

Genus Host Details Tissue Tropism Entry Details Release Details Replication Site Assembly Site Transmission
Corticovirus Bacteria None Injection Lysis Cytoplasm Cytoplasm Passive diffusion


  1. ^ a b "Viral Zone". ExPASy. Retrieved 15 June 2015. 
  2. ^ a b ICTV. "Virus Taxonomy: 2014 Release". Retrieved 15 June 2015. 
  3. ^ Krupovic M, Bamford DH (2007). "Putative prophages related to lytic tailless marine dsDNA phage PM2 are widespread in the genomes of aquatic bacteria" (PDF). BMC Genomics 8: 236. doi:10.1186/1471-2164-8-236. PMC 1950889. PMID 17634101. 
  4. ^ Kiveld, H.M., Kalkkinen, N. and Bamford, D.H. (2002). Bacteriophage PM2 has a protein capsid surrounding a spherical lipid-protein core" J. Virol 76, 8169-8178.
  5. ^ Kiveld, H.M., Männistö, R.H., Kalkkinen, N. and Bamford, D.H. (1999). Purification and protein composition of PM2, the first lipid-containing bacterial virus to be isolated" Virology 262, 364-374.
  6. ^ Harrison, S.C., Caspar, D.L., Camerini-Otero, R.D. and Franklin, R.M. (1971). Lipid and protein arrangement in bacteriophage PM2. Nat. New Biol., 229, 197-201.
  7. ^ Männistö, R.H., Kivelä, H.M., Paulin, L., Bamford, D.H. and Bamford, J.K.H. (1999). The complete genome sequence of PM2, the first lipid-containing bacterial virus to be isolated" Virology 262, 355-363.

External links[edit]