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:
- Group I: Double-stranded DNA (dsDNA) viruses–Herpes virus, Adenovirus,Poxvirus
- Group II: Single stranded DNA (ssDNA) viruses– Parvovirus
- Group III: Double-stranded RNA (dsRNA) viruses-Rotavirus
- Group IV: Positive sense single-stranded RNA (+ssRNA) viruses–SARS-CoV-2
- Group V: Negative sense ssRNA (-ssRNA) viruses–Influenza virus
- Group VI: Single strand RNA retroviruses (ssRNA-RT)-HIV
- 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 |
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)