Classification and nomenclature of viruses

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The International Committee on Nomenclature of Viruses (ICNV) was established in 1966 to develop a single universal taxonomic scheme. The successor to the ICNV, the International Committee on Taxonomy of Viruses (ICTV), established in 1973, developed and expanded the universal scheme in which virion characteristics are used to assign viruses to five main hierarchical levels, namely order, family, subfamily, genus and species.

Classification and nomenclature of viruses:

Hierarchical classification:

  • Kingdom
  • Phylum
  • Class
  • Order(–virales)
  • Family(–viridae)
  • Genus(–virus)
  • Species

Based on-

  • Classification based on epidemiology:Enteric virus,Respiratory virus,Arbovirus
  • Nature & sequence of nucleic acid: RNA,DNA,circular,linear,positive sense,negative sense
  • Symmetry of protein cell(Capsid)– Icosahedral,Helical,Complex
  • Presence or absence of lipid membrane(envelope): Enveloped virus,Naked virus
  • Dimension of virus particle

Baltimore classification:

  1. Group I: Double-stranded DNA (dsDNA) viruses–Herpes virus, Adenovirus,Poxvirus
  2. Group II: Single stranded DNA (ssDNA) viruses– Parvovirus
  3. Group III: Double-stranded RNA (dsRNA) viruses-Rotavirus
  4. Group IV: Positive sense single-stranded RNA (+ssRNA) viruses–SARS-CoV-2
  5. Group V: Negative sense ssRNA (-ssRNA) viruses–Influenza virus
  6. Group VI: Single strand RNA retroviruses (ssRNA-RT)-HIV
  7. Group VII: Double-stranded DNA retroviruses (dsDNA-RT)- Hepatitis B

Virus Families and their properties(at a glance):

 

Genome Virus Genome Type Capsid Symmetry Morphology Envelope Replication Isolation Virus Under These Families
ssRNA+ Arteriviridae Linear Icosahedral Sperical Enveloped Cytoplasm
Astroviridae Linear Icosahedral Isometric Non-Enveloped Cytoplasm
Caliciviridae Linear Icosahedral Isometric Non-Enveloped Cytoplasm Vesicular Exanthema of Swine
Coronaviridae Linear Helical Sperical Enveloped Cytoplasm Allantoic Cavity Infectious Bronchitis,SARS-CoV-2
Flaviviridae Linear Icosahedral Sperical Enveloped Cytoplasm Bovine Viral Diarrhoea, Classical Swine fever
Hepevirus (unassigned) Linear Icosahedral Isometric Non-Enveloped Cytoplasm
Picornaviridae Linear Icosahedral Isometric Non-Enveloped Cytoplasm FMD
Retroviridae Un-Segmented-Diploid Icosahedral Sperical Enveloped Nucleus   Avian Leukosis Virus, Bovine Leukaemia
Togaviridae Linear Icosahedral Sperical Enveloped Cytoplasm Yolk Sac
ssRNA- Arenaviridae 2 segments Helical Sperical Enveloped Cytoplasm
Bunyaviridae 3 segments Helical Sperical Enveloped Cytoplasm Rift valley fever
Bornaviridae Linear Icosahedral Sperical Enveloped Nucleus  
Filoviridae Linear Helical Filamentous Enveloped Cytoplasm
Orthomyxoviridae 6–8 segments Helical Pleomorphic Enveloped Nucleus Allantoic Cavity,Amniotic Cavity Influenza- Swine, Equine Influneza, Avian Influenza
Paramyxoviridae Linear Helical Pleomorphic Enveloped Cytoplasm Allantoic Cavity New castle, Mumps, Measles, Avian pneumonia, PPR, Rinderpest, Canine distemper
Rhabdoviridae Linear Helical Bullet-shaped Enveloped Cytoplasm Vesicular stomatitis, Rabies, Bovine ephemeral fever
dsRNA Birnaviridae 2 segments Icosahedral Isometric Non-Enveloped Cytoplasm IBD
Reoviridae 10–12 segments Icosahedral Isometric Non-Enveloped Cytoplasm Yolk Sac,Allantoic,Blue tongue- IV Blue tongue, Rota virus A, Colorado tick fever, African Horse sickness
ssDNA Circoviridae Un-Segmented-Circular Icosahedral Isometric Non-Enveloped Nucleus Porcine circo, Chicken anaemia
Parvoviridae Linear Icosahedral Isometric Non-Enveloped Nucleus
dsDNA Adenoviridae Linear Icosahedral Isometric Non-Enveloped Nucleus Yolk Sac Fowl adenovirus, Ovine adeno virus
Asfarviridae Linear Icosahedral Sperical Enveloped Cytoplasm   African swine fever
Herpesviridae Linear Icosahedral Isometric Enveloped Nucleus Gallid herpes virus 1,2, Equine herpes 2
dsDNA-RT Hepadnaviridae Linear Icosahedral Sperical Enveloped Nucleus Duck hepatitis, Hepatitis B
dsDNA Papillomaviridae Un-Segmented-Circular Icosahedral Isometric Non-Enveloped Nucleus
Polyomaviridae Un-Segmented-Circular Icosahedral Isometric Non-Enveloped Nucleus Simian virus-40
Poxviridae Linear Complex Pleomorphic Enveloped Cytoplasm CAM Orthopox,Suipox,Parapox,Yata pox,Capri pox

Virus Family Details

Important features of Virus nomenclature:

  • The papovaviruses (sigla: pa = papilloma; po = polyoma; va — vacuolating agent) :Papillomavirus (wart viruses),Polyomavirus
  • adenoviruses (adeno = gland)
  • herpesviruses (herpes = creeping)
  • Iridoviridae (irido =iridescent)
  • poxviruses (pock = pustule)
  • Parvoviruses (parvus = small)
  • Hepadnaviridae (hepa = liver; dna)
  • Picornaviridae (name originally derived from poliovirus, insensitivity to ether, coxsackievirus, orphan virus, rhinovirus, and ribonucleic acid (omitting one “r”), but conveniently also consistent with the sigla, pico = small; rna= ribonucleic acid)
  • caliciviruses (calix = cup)
  • togaviruses (toga = cloak)
  • (flavi = yellow)
  • orthomyxoviruses (myxo = mucus)
  • Morbillivirus (morbilli = measles), and Pneumovirus (pneumo = lung)
  • coronaviruses (corona = crown)
  • Areanviruses (arena = sand)
  • Retro: This name (sigla: re = reverse; tr = transcriptase)
  • Oncovirinae(onkos = tumor)
  • Lentivirinae (lenti = slow)
  • Spumavirinae (spuma = foam)
  • rhabdoviruses (rhabdos = rod)
  • Orbivirus (orbi = ring) and Rotavirus (rota =wheel)
  • Birna(sigla: bi = two; ma)
  • Filoviridae(filum = thread)
  • Toroviridae (torus = object shaped like a donut)
  • Astrovirus (astro = star)