The virus

Virus

A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

 genus Densovirus belongs to the Densovirinae subfamily which belongs to the Parvoviridae

Parvoviridae

The Parvoviridae family includes the smallest known viruses, and some of the most environmentally resistant. They were discovered during the 1960s and affect vertebrates and insects...

 family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

. The viruses of this genus are single-stranded DNA viruses (and are thus group II viruses under the Baltimore classification

Baltimore classification

The Baltimore classification, developed by David Baltimore, is a virus classification system that groups viruses into families, depending on their type of genome and their method of replication....

). The viruses of this genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 are invertebrate viruses, infecting crustacean

Crustacean

Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s and insects. Examples of species classified into this genus include Aedes albopictus densovirus, Galleria mellonella densovirus, and Junonia coenia densovirus.

Structure

These virions consist of non-enveloped capsids that have a round appearance and display icosahedral symmetry. The virions each have an isometric (and therefore spherical) nucleocapsid with a diameter of either 18-22 nm or 20-26 nm. Sixty capsomers are present in each capsid. The structure of each capsomer is described as "a quadrilateral 'kite-shaped' wedge"; the surface is said to have a rough appearance with small projections. The centre of capsids are sometimes visualised as appearing dark due to stain penetration in preparations where only a single species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 is retrieved. The virions do not appear to contain lipids. The buoyant density (in CsCl) of the virions is 1.4-1.44 g cm⁻³.

Genome

These viruses have non-segmented genomes that contains a single linear molecule of single-stranded DNA. The genome codes for structural proteins and is 5000 nucleotides in length and could either be negative-sense or positive-sense. Conserved nucleotide sequences of usually 120-300 or more nucleotides are present at the 3'-terminus and an inverted repeat

Inverted repeat

An inverted repeat is a sequence of nucleotides that is the reversed complement of another sequence further downstream.For example, 5'---GACTGC....GCAGTC---3'. When no nucleotides intervene between the sequence and its downstream complement, it is called a palindrome. Inverted repeats define the...

of this could also be found at the 5'-terminus.

External links

• ViralZone: Densovirus