DESCRIPTION OF VIRUSES

Family Birnaviridae

Genus Entomobirnavirus

Genus Entomobirnavirus

Type Species

Drosophila X virus

(DXV)

Distinguishing Features

Species of genus infect only insects.

List of Species Demarcation Criteria in the Genus

Not applicable.

List of Species in the Genus

Official virus species names are in italics. Tentative virus species names, alternative names ( ), strains or serotypes are not italicized. Virus name and assigned abbreviation ( ) are:

Species in the Genus

Drosophila X virus

(DXV)

Tentative Species in the Genus

None reported.

List of Unassigned Viruses in the Family

Rotifer birnavirus (Brachiorus plicatilis)

(RBV)

Picobirnavirus, the proposed name for a novel genus of viruses recently detected in children and several species of animals are different from the existing members of the family Birnaviridae. These viruses are 30-40  nm in diameter and have icosahedral symmetry with triangulation number T = 3. Their buoyant density in CsCl is 1.4  g/cm3. Their genome is bi- or trisegmented dsRNA with segment lengths of 2.6 and 1.9  kbp for the bisegmented members of the group and 2.9, 2.4, and 0.9  kbp for the trisegmented genomes. The viruses are detected in the fecal material of animals with and without diarrhea.

Phylogenetic Relationships within the Family

See Fig. 4.

Similarity with Other Taxa

Birnaviruses share no nucleic acid sequence similarity with other taxa. At the protein sequence level, the protein encoded by the A segment has no similarity with any other virus family. There is also no antigenic similarity detectable by antisera cross-reactivity. The RNA-dependent RNA polymerase (RdRp) encoded by segment B, does display evidence of conservation with other viral RdRps. The birnavirus RdRps contain a hydrophylic, higly basic domain in the carboxy-proximal region of the protein. Within this domain are conserved amino-acids in positions that are found in other RdRps, particularly those of dsRNA viruses such as reoviruses. The sequence conservation, however, is not sufficient to be detectable with any standard algorithm for phylogenetic relatedness.

Derivation of Names

Aqua: from Latin aqua, “water”.

Avi: from Latin avis, “bird”.

Bi: from Latin prefix bi, “two”, signifies the bisegmented nature of the viral genome as well as the presence of dsRNA.

Entomo: from Greek entomon, “insect”.

Rna: sigla from ribo nucleic acid, indicating the nature of the viral genome.


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