The nomenclature of
viruses has been in a constant state of flux for many years. This is
may not be
unconnected with emerging facts about the composition and morphology of
viruses with advanced
studies made possible by new technologies.
Some
viruses are named according to the type of disease they cause. Examples include
poxviruses,
herpesviruses (creeping lesions)
Other
are named based on acronyms of disease (papovavirus -papilloma, -polyoma –
vacuolating)
or acronym of observable characteristics (picornavirus -pico/small –
rna
–virus)
Viruse
are also named based on morphology as revealed by electron microscopy.
Coronaviruses
(halo or corona/crown of spikes), Togavirus (Toga/cloak), Rhabdovirus
(Rhabdo/Rod-shaped),
Calicivirus (Calix/cup-shaped depression)
Some
viruses are named after geographical regions where they were first isolated (E.
g.
Coxsackie-,
Marburg-, Gumboro-, Mokola- virus)
Occasionally,
viruses are named after individual discoverer (Epstein-Barr virus)
The International
Committee on Taxonomy of Viruses (ICTV) was established in 1973 to
develop and expand
the universal scheme in which characteristics of virions are used to
assign them to five
hierarchical levels (order, family, subfamily, genus and species). The
hierarchical levels
are denoted with the following suffixes:
Order: -virale
Family: -viridae
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Subfamily: -virinae
Genus: -virus
Species: -virus
The primary considerations
for virus taxonomy are the type and nature of the genome, the
mode and site of
replication and the structure and morphology of the virion.
Virus orders are
designated by the suffix –virale. Phylogenetically-related families are
grouped together.
Many virus families are yet to be assigned into orders. Only two orders
containing viruses of
animals are so far recognized. The virus order Mononegavirale is
made up the families
Paramyxoviridae, Rhabdoviridae, Bornaviridae and Filoviridae.
Members of the order
Mononegavirale have common attributes including a single
stranded,
non-segmented, negative sense RNA genome. Their replication strategies are
also similar. The
second viral order is the Nidovirale comprising of the families
Coronaviridae and
Arteriviridae.
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