Navigation Links
Virus classification


Viruses can be classified in several ways, such as by their geometry, by whether they have envelopes, by the identity of the host organism they can infect, by mode of transmission, or by the type of disease they cause. The most useful classification is probably by the type of nucleic acid the virus contains and its mode of expression. This classification was proposed by Nobel-prize winner David Baltimore. It should be noted that none of these classifications are expected to be phylogenetic, as viruses may not share a common origin.

Contents
1 Overview
2 Classification by genome type

2.1 DNA viruses

2.1.1 Group I - dsDNA viruses (double stranded DNA)
2.1.2 Group II - ssDNA viruses (single stranded DNA)

2.2 RNA viruses

2.2.1 Group III - dsRNA viruses (double stranded RNA)
2.2.2 Group IV - (+)ssRNA viruses (positive single stranded RNA or mRNA like)
2.2.3 Group V - (-)ssRNA viruses (negative single-stranded RNA)

2.3 DNA and RNA Reverse Transcribing viruses

2.3.1 Group VI - ssRNA-RT viruses (single stranded RNA)
2.3.2 Group VII - dsDNA-RT viruses (double stranded DNA)

3 Subviral agents

3.1 Viroids
3.2 Satellites
3.3 Prions

4 Other resources

4.1 External links
4.2 See also

Overview

The various forms of viruses arise because one of the two strands of DNA in which all cellular life forms store their genetic information is redundant, so that viruses can have either single-stranded or double-stranded genomes. Furthermore, some viruses store their genome in RNA rather than in DNA form. RNA arises in cells as an intermediate when genes are translated into proteins. RNA genomes of viruses can be encoded in two different directions: Either the genes are stored in the 5'->3' direction (positive or + polarity), analogous to the direction in which genes are represented in mRNA in cells, or the genes are stored in the opposite direction (negative or - polarity).

The taxonomy of viruses is similar to that of cellular organisms:

Order (-virales)
Family (-viridae)
Subfamily (-virinae)
Genus (-virus)
Species

However, the code of nomenclature regulated by the International Committee on Taxonomy of Viruses differs from the others on several points. Most notably, names of orders and families are italicized, and species names are not binomial - instead, they generally take the form of [Disease] Virus. The recognition of orders is very recent and has been deliberately slow; to date, only three have been named, and most families remain unplaced. Approximately 80 families and 4000 species of virus are known.

Classification by genome type

DNA viruses

Group I - dsDNA viruses (double stranded DNA)

Group II - ssDNA viruses (single stranded DNA)

RNA viruses

Group III - dsRNA viruses (double stranded RNA)

Group IV - (+)ssRNA viruses (positive single stranded RNA or mRNA like)

Group V - (-)ssRNA viruses (negative single-stranded RNA)

DNA and RNA Reverse Transcribing viruses

Group VI - ssRNA-RT viruses (single stranded RNA)

Group VII - dsDNA-RT viruses (double stranded DNA)

Subviral agents

The following agents are smaller than viruses but have some of their properties.

Viroids

  • Family Pospiviroidae
    • Genus Pospiviroid; type species: Potato spindle tuber viroid
    • Genus Hostuviroid ; type species: Hop stunt viroid
    • Genus Cocadviroid ; type species: Coconut cadang-cadang viroid
    • Genus Apscaviroid ; type species: Apple scar skin viroid
    • Genus Coleviroid ; type species: Coleus blumei viroid 1
  • Family Avsunviroidae
    • Genus Avsunviroid ; type species: Avocado sunblotch viroid
    • Genus Pelamoviroid ; type species: Peach latent mosaic viroid

Satellites

  • Satellite viruses
    • Single-stranded RNA satellite viruses
      • Sugroup 1: Chronic bee-paralysis satellite virus
      • Subgroup 2: Tobacco necrosis satellite virus
  • Satellite nucleic acids
    • Single-stranded satellite DNAs
    • Double-stranded satellite RNAs
    • Single-stranded satellite RNAs
      • Subgroup 1: Large satellite RNAs
      • Subgroup 2: Small linear satellite RNAs
      • Subgroup 3: Circular satellite RNAs

Prions

  • Fungal prions
  • Mamalian prions

Other resources

External links

See also


'"/>


(Date:11/25/2009)...sistant professors recently received funding from ...research beneficial to understanding the environme...er Blackwood, assistant professor in the Departmen...pport two separate research projects. , His firs...mmunities and Functions from the Leaf to the Lands...
(Date:11/24/2009)... a protein that may help gut bacteria bind to the ...by probiotic producers to identify strains that ar...iotics need to interact with cells lining the gut ... surfaces in the gut they are more likely to stick... Dr Nathalie Juge from the Institute of Food Resea...
(Date:11/24/2009)...s long held secrets of the earth,s history locked ...een very little information on the environments th...ons of years. Now, a team of researchers from nine...the tune of $10 million dollars by the National Sc...things literally. These scientists will drill thr...
Breaking Biology News(10 mins):Kent State University professors focus research on the environment with grants totaling $890,000 2A sticky solution for identifying effective probiotics 2LSU gets to the bottom of things -- in Antarctica 2VIVIMIND 28TM 29 granted certificate of free sale as food supplement in Italy Premarket notification filed in the U S 51966 1VIVIMIND 28TM 29 granted certificate of free sale as food supplement in Italy Premarket notification filed in the U S 51966 2VIVIMIND 28TM 29 granted certificate of free sale as food supplement in Italy Premarket notification filed in the U S 51966 3Omnicell to Release Second Quarter 2009 Earnings Results on July 23 51961 1Omnicell to Release Second Quarter 2009 Earnings Results on July 23 51961 2Caliper Life Sciences Second Quarter 2009 Financial Results Conference Call Notice 13071 1Caliper Life Sciences Second Quarter 2009 Financial Results Conference Call Notice 13071 2
...nant women or those hoping to start or extend a fa...rugs statins, say scientists. , Current clinical ...egnant should stop taking statins but the advice i...tial for normal fetal development. , Indeed, a 20...s in children of pregnant women using statins sugg...
...rn day concentrations of ground level ozone pollut...hern and temperate mid-latitudes, as shown in a pa...Tree growth, measured in biomass, is already 7% le...e to a 17% reduction by the end of the century. , ...ior to the Industrial Revolution in the mid-1700s;...
... Dec. 8 Building off of the momentum of,September...mity &,Interoperability Tests, Entrust, Inc. (...ePassport leader by being selected to supply the C...ond-generation ePassports based on the,Extended Ac...ation ePassports represent the beginning of an evo...
Other Biology News:Statin warning for pregnant women 2Surface-level ozone pollution set to reduce tree growth 10 percent by 2100 2The Finnish Population Register Centre to Deploy Entrust EAC ePassport CA Solution 2The Finnish Population Register Centre to Deploy Entrust EAC ePassport CA Solution 3The Finnish Population Register Centre to Deploy Entrust EAC ePassport CA Solution 4
Other biology definitionOther TagsReinforceGISTGISTGISTGISTGISTIPIIPIIPIIPIIPIIPI