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Virus classification involves naming and placing viruses into a taxonomic system. A virus (from the Latin virus meaning Toxin or Poison) is a sub-microscopic infectious agent that is unable Taxonomy, sometimes alpha taxonomy, is the Science of finding describing and categorising Organisms thus giving rise to taxonomic groups or taxa Like the relatively consistent classification systems seen for cellular organisms, virus classification is the subject of ongoing debate and proposals. The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called This is largely due to the pseudo-living nature of viruses, which are not yet definitively living or non-living. A virus (from the Latin virus meaning Toxin or Poison) is a sub-microscopic infectious agent that is unable As such, they do not fit neatly into the established biological classification system in place for cellular organisms, such as plants and animals.

Virus classification is based mainly on phenotypic characteristics, including morphology, nucleic acid type, mode of replication, host organisms, and the type of disease they cause. A phenotype is any observable characteristic of an Organism, such as its morphology, Development, biochemical or physiological properties A virus (from the Latin virus meaning Toxin or Poison) is a sub-microscopic infectious agent that is unable A nucleic acid is a Macromolecule composed of chains of monomeric Nucleotides In Biochemistry these Molecules carry Genetic information In Biology, a host is an organism that harbors a Virus or Parasite, or a mutual or Commensal Symbiont, typically providing nourishment A disease is an abnormal condition of an organism that impairs bodily functions and can be deadly A combination of two main schemes is currently in widespread use for the classification of viruses. David Baltimore, a Nobel Prize-winning biologist, devised the Baltimore classification system, which places viruses into one of seven groups. David Baltimore (born March 7, 1938) is an American biologist The Nobel Prize (Nobelpriset (Nobelprisen is a Swedish prize established in the 1895 will of Swedish chemist Alfred Nobel; it was first awarded in Peace, Literature The Baltimore classification is a Virus classification system which groups Viruses into families depending on their type of Genome ( DNA These groups are designated by Roman numerals and separate viruses based on their mode of replication, and genome type. Roman numerals are a Numeral system originating in ancient Rome, adapted from Etruscan numerals. Accompanying this broad method of classification are specific naming conventions and further classification guidelines set out by the International Committee on Taxonomy of Viruses. The International Committee on Taxonomy of Viruses ( ICTV) is a committee which authorizes and organizes the taxonomic classification of Viruses They have

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Baltimore classification

Main article: Baltimore classification
The Baltimore Classification of viruses is based on the method of viral mRNA synthesis
The Baltimore Classification of viruses is based on the method of viral mRNA synthesis

Baltimore classification (first defined in 1971) is a classification system which places viruses into one of seven groups depending on a combination of their nucleic acid (DNA or RNA), strandedness (single-stranded or double-stranded), and method of replication. The Baltimore classification is a Virus classification system which groups Viruses into families depending on their type of Genome ( DNA Messenger ribonucleic acid ( mRNA) is a molecule of RNA encoding a chemical "blueprint" for a Protein product A nucleic acid is a Macromolecule composed of chains of monomeric Nucleotides In Biochemistry these Molecules carry Genetic information Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known Ribonucleic acid ( RNA) is a Nucleic acid that consists of a long chain of Nucleotide units Chronic since 1992 ( talk) 2200 12 December 2007 (UTC --> Viral replication Other classifications are determined by the disease caused by the virus or its morphology, neither of which are satisfactory due to different viruses either causing the same disease or looking very similar. In addition, viral structures are often difficult to determine under the microscope. Classifying viruses according to their genome means that those in a given category will all behave in a similar fashion, offering some indication of how to proceed with further research. In classical genetics the genome of a Diploid Organism including Eukarya refers to a full set of chromosomes or genes in a Gamete, thereby Viruses can be placed in one of the seven following groups:[1]

DNA viruses

For more details on this topic, see DNA virus. Hepadnaviruses are a family of Viruses which can cause Liver infections in humans and animals A DNA virus is a Virus that has DNA as its Genetic material and replicates using a DNA-dependent DNA polymerase.
Virus Family Examples (common names) Virion- naked/enveloped Capsid Symmetry Type of nucleic acid
1. Adenoviridae Adenovirus Naked Icosahedral ds
2. Adenoviruses are medium-sized (90–100 nm) Nonenveloped (naked Icosahedral viruses composed of a nucleocapsid and a double-stranded linear DNA Papovaviridae Papillomavirus Naked Icosahedral ds circular
3. A Papovaviridae is a member of the Papovaviridae family of Viruses Papovaviridae includes two genera: Papillomavirus and Parvoviridae Parvovirus B19 Naked Icosahedral ss
4. The Parvoviridae family includes the smallest known Viruses and some of the most environmentally resistant Herpesviridae Herpes simplex virus, varicella-zoster virus, cytomegalovirus, Epstein-Barr virus Enveloped Icosahedral ds
5. The Herpesviridae are a large family of DNA viruses that cause diseases in animals including humans Poxviridae Smallpox virus, vaccinia virus Complex coats Complex ds
6. Poxviruses (members of the family Poxviridae) are viruses that can as a family infect both Vertebrate and Invertebrate animals Hepadnaviridae Hepatitis B virus Enveloped Icosahedral circular, partially ds
7. Hepadnaviruses are a family of Viruses which can cause Liver infections in humans and animals Polyomaviridae Polyoma virus; JC virus (progressive multifocal leucoencephalopathy) Naked Icosahedral ds circular

RNA viruses

For more details on this topic, see RNA virus. Polyomavirus is the sole Genus of Viruses within the family Polyomaviridae. An RNA virus is a Virus that has RNA (ribonucleic acid as its Genetic material.
Virus Family Examples (common names) Virion- naked/enveloped Capsid Symmetry Type of nucleic acid
1. Reoviridae Reovirus, Rotavirus Naked Icosahedral ds
2. Reoviridae is a family of Viruses that can affect the Gastrointestinal system (such as Rotavirus) and Respiratory tract Reoviridae is a family of Viruses that can affect the Gastrointestinal system (such as Rotavirus) and Respiratory tract Rotavirus is a Genus of Double-stranded RNA virus in the family Reoviridae. Picornaviridae Enterovirus, Rhinovirus, Hepatovirus, Cardiovirus, Aphthovirus, Poliovirus, Parechovirus, Erbovirus, Kobuvirus, Teschovirus, Coxsackie Naked Icosahedral ss
3. A Picornavirus is a Virus belonging to the family Picornaviridae. The enteroviruses are a genus of (+ssRNA viruses associated with several human and mammalian diseases Rhinovirus (from the Greek rhin - which means "nose" is a genus of the Picornaviridae family of Viruses Rhinoviruses Hepatitis A, (formerly known as infectious hepatitis) is an acute Infectious disease of the Liver caused by Hepatitis A virus which is Cardiovirus is a genus within the family Picornaviridae. The genus is comprised of two species Encephalomyocarditis virus and Theilovirus Poliovirus, the causative agent of Poliomyelitis, is a human Enterovirus and member of the family of Picornaviridae. Parechovirus is a Viral Genus in the family Picornaviridae. The genus is composed of two species Human parechovirus Erbovirus is a viral Genus of the Picornaviridae family Viruses belonging to the Erbovirus genus have been isolated Kobuvirus is a viral Genus belonging to the family Picornaviridae. The Teschovirus is a genus of the Picornaviridae family This virus is responsible for the porcine enteroviral encephalomyelitis disease caused in pigs. Caliciviridae Norwalk virus, Hepatitis E virus Naked Icosahedral ss
4. The Caliciviridae family are a family of Viruses, members of Class IV of the Baltimore scheme. Norovirus (was "Norwalk-like viruses" an RNA virus of the Caliciviridae taxonomic family, causes approximately 90% of Epidemic Hepatitis E is a viral Hepatitis (liver inflammation caused by Infection with a Virus called hepatitis E virus ( HEV) Togaviridae Rubella virus Enveloped Icosahedral ss
5. The Togaviridae are a family of Viruses including the following genera Genus Alphavirus; type species Sindbis virus This page is for the virus For the disease see Rubella. Rubella virus is an enveloped, single-stranded RNA virus and the only Arenaviridae Lymphocytic choriomeningitis virus Enveloped Complex ss
6. Arenavirus is a genus of Virus. The type species is Lymphocytic choriomeningitis virus (LCMV; it also includes the species responsible for Lymphocytic choriomeningitis (LCM is a Rodent -borne viral infectious disease that presents as aseptic Meningitis, Encephalitis or Meningoencephalitis Flaviviridae Dengue virus, Hepatitis C virus, Yellow fever virus Enveloped Icosahedral ss
7. The Flaviviridae are a family of Viruses that are primarily spread through arthropod vectors (mainly ticks and mosquitoes Hepatitis C is a blood-borne infectious disease that is caused by the Hepatitis C virus ( HCV) affecting the Liver. Yellow fever (also called yellow jack, black vomit or sometimes American Plague) is an acute viral disease Orthomyxoviridae Influenzavirus A, Influenzavirus B, Influenzavirus C, Isavirus, Thogotovirus Enveloped Helical ss
8. The Orthomyxoviridae (Derivation of name orthos is Greek for straight myxa is Greek for Mucus) are a family of RNA viruses that Influenzavirus A is a Genus of the Orthomyxoviridae family of Viruses Influenzavirus A includes only one Species: Influenza A virus Influenzavirus B is a genus in the Virus family Orthomyxoviridae. Influenzavirus C is a genus in the Virus family Orthomyxoviridae, which includes those Viruses which cause Influenza. Infectious salmon anemia or anaemia ( ISA) is a viral Disease of Atlantic Salmon ( Salmo salar) that affects fish farms Thogotovirus is a genus in the Virus family Orthomyxoviridae. Paramyxoviridae Measles virus, Mumps virus, Respiratory syncytial virus Enveloped Helical ss
9. Paramyxoviruses are Viruses of the Paramyxoviridae family of the Mononegavirales order they are negative-sense single-stranded Measles (rubeola is a Disease caused by a virus specifically a Paramyxovirus of the genus Morbillivirus. Mumps or epidemic Parotitis is a Viral disease of the Human species Human respiratory syncytial virus (RSV is a negative-sense single-stranded RNA virus of the family Paramyxoviridae, which includes Bunyaviridae California encephalitis virus, Hantavirus Enveloped Helical ss
10. Bunyaviridae is a family of negative-stranded RNA viruses Though generally found in Arthropods or rodents certain viruses in this family occasionally infect California encephalitis virus causes Encephalitis in humans Mosquitos serve as its vectors For this reason this virus is known as an Arbovirus Hantaviruses belong to the Bunyaviridae family of Viruses There Bunyaviridae family is divided into 5 genera Rhabdoviridae Rabies virus Enveloped Helical ss
11. Rhabdoviruses are Viruses belonging to the family Rhabdoviridae, which is in the order Mononegavirales. Rabies (from rabies “madness rage fury” Also known as “ hydrophobia ” is a viral Zoonotic neuroinvasive disease that Filoviridae Ebola virus, Marburg virus Enveloped Helical ss
12. Filoviridae is the family of Viruses that belong to the order Mononegavirales. Ebola is the common term for a group of Viruses belonging to genus Ebolavirus, family Filoviridae, and for the disease which they The Marburg virus is the causative agent of Marburg haemorrhagic fever (also known as green monkey disease) Coronaviridae Corona virus Enveloped Helical ss
13. Coronaviruses are enveloped single stranded positive-sense RNA viruses (27-31kb with club-shaped surface about 120-160 nm in diameter that resemble a “corona” Coronavirus is a genus of animal Virus belonging to the family Coronaviridae. Astroviridae Astrovirus Naked Icosahedral ss
14. Astrovirus is a type of Virus that infects Mammals and Birds. Astrovirus is a type of Virus that infects Mammals and Birds. Bornaviridae Borna disease virus Enveloped Helical ss

Reverse transcribing viruses

For more details on this topic, see Reverse transcribing virus. BDV redirects here for Big Daddy V see Nelson Frazier Jr Borna disease is an infectious Neurological syndrome of BDV redirects here for Big Daddy V see Nelson Frazier Jr Borna disease is an infectious Neurological syndrome of A reverse transcribing virus is any virus which replicates using Reverse transcription, the formation of DNA from an RNA template

ICTV classification

The International Committee on Taxonomy of Viruses began to devise and implement rules for the naming and classification of viruses early in the 1990s, an effort that continues to the present day. The International Committee on Taxonomy of Viruses ( ICTV) is a committee which authorizes and organizes the taxonomic classification of Viruses They have The system shares many features with the classification system of cellular organisms, such as taxon structure. A taxon (plural taxa) or taxonomic unit, is a name designating an organism or a group of Organisms In Biological nomenclature according to Viral classification starts at the level of order and follows as thus, with the taxon suffixes given in italics:

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

So far, only three orders have been established by the ICTV: Caudovirales, Mononegavirales, and Nidovirales. This article is about the taxonomic rank for the sequence of species in a taxonomic list see Taxonomic order In scientific classification used In Biological classification, family ( Latin A genus (plural genera from Γένος Latin genus "descent family type gender" is a low-level Taxonomic In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. These orders span viruses with varying host ranges. Caudovirales are tailed dsDNA (group I) bacteriophages, Mononegavirales includes non-segmented (-)ss-RNA (Group V) plant and animal viruses, and Nidovirales is composed of (+)-ssRNA (Group IV) viruses with vertebrate hosts. The Caudovirales are an order of Viruses better known as the tailed Bacteriophages. The Mononegavirales are an order of Viruses comprising species that have a Non-segmented, negative sense RNA Genome The Nidovirales are an order of Viruses with Vertebrate hosts Other variations occur between the orders, for example, Nidovirales are isolated for their differentiation in expressing structural and non-structural proteins separately. However, this system of nomenclature differs from other taxonomic codes on several points. A minor point is that names of orders and families are italicized, as in the ICBN. The International Code of Botanical Nomenclature ( ICBN) is the set of rules and recommendations dealing with the formal Botanical names that are given to [2] Most notably, species names 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.

Holmes classification

Holmes (1948) used Carolus Linnaeus system of binomial nomenclature classification system to viruses into 3 groups under one order, Virales. Carl Linnaeus (Latinized as Carolus Linnaeus, also known after his ennoblement as, May 23 new style (13 May old style 1707 who laid the foundations for They are placed as follows:

LHT System of Virus Classification

The LHT System of Virus Classification is based on chemical and physical characters like nucleic acid (DNA or RNA), Symmetry (Helical or Icosahedral or Complex), presence of envelope, diameter of capsid, number of capsomers. This article is about a biological infectious particle for other uses see Phage (disambiguation. For the leaf bug see Miridae. A capsid is the protein shell of a virus. [3] This classification was approved by the Provisional Committee on Nomenclature of Virus (PNVC) of the International Association of Microbiological Societies (1962). It is as follows:

  • Subphylum Deoxyvira (DNA viruses)
  • Class Deoxybinala (dual symmetry)
  • Order Uroviridae
  • Family Phagoviridae
  • Class Deoxyhelica (Helical symmetry)
  • Order Chitovirales
  • Family Poxviridae
  • Class Deoxycubica (cubical symmetry)
  • Order Peplovirales
  • Family Herpesviridae (162 capsomeres)
  • Order Haplovirales (no envelope)
  • Family Iridoviridae (812 capsomeres)
  • Family Adenoviridae (252 capsomeres)
  • Family Papiloviridae (72 capsomeres)
  • Family Paroviridae (32 capsomeres)
  • Family Microviridae (12 capsomeres)
  • Subphylum Ribovira (RNA viruses)
  • Class Ribocubica
  • Order Togovirales
  • Family Arboviridae
  • Order Lymovirales
  • Family Napoviridae
  • Family Reoviridae
  • Class Ribohelica
  • Order Sagovirales
  • Family Stomataviridae
  • Family Paramyxoviridae
  • Family Myxoviridae
  • Order Rbadovirales
  • Suborder Flexiviridales
  • Family Mesoviridae
  • Family Peptoviridae
  • Suborder Rigidovirales
  • Family Pachyviridae
  • Family Protoviridae
  • Family Polichoviridae

Casjens and Kings classification of virus

Casjens and Kings(1975) classified virus into 4 groups based on type of nucleic acid, presence of envelope, symmetry and site of assembly. It is as follows:

Subviral agents

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

Viroids

Satellites

Satellites depend on co-infection of a host cell with a helper virus for productive multiplication. Viroids are Plant Pathogens that consist of a short stretch (a few hundred nucleobases) of highly complementary circular single-stranded The Pospiviroidae are a family of Viroids including the first viroid to be discovered PSTVd. Pospiviroid is a Genus of Viroid which most commonly infects tubers The Potato spindle tuber viroid ("PSTVd" was the first Viroid to be identified The Avsunviroidae are a family of Viroids. At present three members are known of Avocado sunblotch viroid (ASBV is an important Disease affecting Avocado Trees Infections result in lower yields and poorer quality fruit Peach latent mosaic Viroid is a type species from the genus Pelamoviroid, which belongs to the family Avsunviroidae. A Satellite is a Subviral agent composed of Nucleic acid that depends on the Coinfection of a host cell with a helper or master Virus for their A helper virus is a virus used when producing copies of a helper dependent viral vector which does not have the ability to replicate on its own Their nucleic acids have substantially distinct nucleotide sequences from either their helper virus or host. When a satellite subviral agent encodes the coat protein in which it is encapsulated, it's then called a satellite virus.

Prions

Prions, named for their description as "proteinaceous and infectious particles," lack any detectable (as of 2002) nucleic acids or virus-like particles. Tobacco necrosis virus (TNV is a plant pathogenic virus of the family Tombusviridae. A virusoid is an infectious agent that infects Plants in conjunction with an assistant Virus; the assistant virus harbors the virusoid and is required for A prion (ˈpriːɒn is thought to be an infectious agent that according to current scientific consensus is comprised entirely of a propagated, mis-folded They resist inactivation procedures which normally affect nucleic acids. [7]

Notes

  1. ^ "Virus Taxonomy Portal." (Website. Transmissible spongiform encephalopathies' ( TSEs, also known as prion diseases) are a group of progressive conditions that affect the Brain and Fungal Prions have been investigated leading to a deeper understanding of disease-forming Mammalian prions Saccharomyces cerevisiae is a Species of Budding Yeast. It is perhaps the most useful Yeast owing to its use since ancient times Saccharomyces cerevisiae is a Species of Budding Yeast. It is perhaps the most useful Yeast owing to its use since ancient times Saccharomyces cerevisiae is a Species of Budding Yeast. It is perhaps the most useful Yeast owing to its use since ancient times ) Viral Bioinformatics Resource Center & Viral Bioinformatics - Canada. Retrieved on 2007-09-27. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 489 - Odoacer attacks Theodoric at the Battle of Verona and is defeated again
  2. ^ The Virus Species Concept: Introduction Virus Taxonomy Online: Seventh Report of the International Committee on Taxonomy of Viruses. 2000. 2000 ( MM) was a Leap year that started on Saturday of the Common Era, in accordance with the Gregorian calendar. Retrieved on 2007-07-14. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1223 - Louis VIII becomes King of France upon the death of his father Philip II of France.
  3. ^ Lwoff A, Horne R, Tournier P (1962). "A system of viruses". Cold Spring Harb. Symp. Quant. Biol. 27: 51–5. PMID 13931895.  
  4. ^ "80.001 Popsiviroidae - ICTVdB Index of Viruses." (Website. ) U. S. National Institutes of Health website. Retrieved on 2007-09-27. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 489 - Odoacer attacks Theodoric at the Battle of Verona and is defeated again
  5. ^ "80.002 Avsunviroidae - ICTVdB Index of Viruses." (Website. ) U. S. National Institutes of Health website. Retrieved on 2007-09-27. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 489 - Odoacer attacks Theodoric at the Battle of Verona and is defeated again
  6. ^ "81. Satellites - ICTVdB Index of Viruses." (Website. ) U. S. National Institutes of Health website. Retrieved on 2007-09-27. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 489 - Odoacer attacks Theodoric at the Battle of Verona and is defeated again
  7. ^ "90. Prions - ICTVdB Index of Viruses." (Website. ) U. S. National Institutes of Health website. Retrieved on 2007-09-27. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 489 - Odoacer attacks Theodoric at the Battle of Verona and is defeated again

See also

Viruses templates

External links

The International Committee on Taxonomy of Viruses ( ICTV) is a committee which authorizes and organizes the taxonomic classification of Viruses They have This is a list of biological viruses See also List of computer viruses This is a list of biological Viruses and types of viruses Taxonomy is the practice and science of classification The word comes from the Greek, taxis (meaning 'order' 'arrangement' and, nomos In biology trinomial nomenclature refers to names for taxa below the rank of species Virology is the study of viruses and virus-like agents: their structure classification and evolution their ways to infect and exploit cells for virus reproduction This is a list of the existing genera of viruses For a list of individual species themselves see List of viruses.
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