The name given to each organism is given using its genus name followed by its species name. The first letter of the name is usually capitalized and the whole name is either italicized or underlined, for instance humans are named: Homo sapiens or Homo sapiens.


Virus Classification

Viruses only display characteristics of living entities only when they are within a host cell and possess unique structural and genetic features. As a result it is not classified in the same way that typical living organisms are.

There are two schemes of classification of viruses; they are Lwoff’s Scheme and Baltimore’s Scheme. These two schemes are discussed briefly below.

Lwoff’s Scheme for Classification

This scheme developed by Lwoff, RW Horne and P Tournier in 1962 make use of shared properties of viruses rather than the host cell or organism they infect. The classification for viruses under this scheme consist of phylum, class, order, family, sub family, genus, species and strain/type.

Four main characteristics used to group the viruses are:

1) Nature of the nucleic acid (DNA or RNA)
2) Capsid symmetry
3) Presence or absence of an envelope
4) Viron and Capsid Dimensons

The international committee on Taxonomy of Viruses (ICTV) has accepted and is using certain principles in this scheme in addition to that of Baltimore’s scheme.


Baltimore’s Scheme for Classification

This scheme developed by David Baltimore uses mechanisms of viral genome replication and the principle that all virus genomes need to construct positive strand RNA from their genomes in to produce virus proteins for replication to categorize viruses.

Various types of virus genomes have different mechanisms for replication and these genomes are grouped into 7 groups which are shown in the diagram below: