''Nodaviridae'' is a family of

nonenveloped A viral envelope is the outermost layer of many types of viruses. It protects the genetic material in their life cycle when traveling between host cells. Not all viruses have envelopes. Numerous human pathogenic viruses in circulation are encase ...

positive-strand RNA virus Positive-strand RNA viruses (+ssRNA viruses) are a group of related viruses that have positive-sense, single-stranded genomes made of ribonucleic acid. The positive-sense genome can act as messenger RNA (mRNA) and can be directly translated int ...

es. Vertebrates and invertebrates serve as natural hosts. Diseases associated with this family include: viral

encephalopathy Encephalopathy (; from grc, ἐνκέφαλος "brain" + πάθος "suffering") means any disorder or disease of the brain, especially chronic degenerative conditions. In modern usage, encephalopathy does not refer to a single disease, but r ...

and

retinopathy Retinopathy is any damage to the retina of the eyes, which may cause vision impairment. Retinopathy often refers to retinal vascular disease, or damage to the retina caused by abnormal blood flow. Age-related macular degeneration is technically inc ...

in fish. There are nine species in the family, assigned to two genera.

History

The name of the family is derived from the

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

ese village of Nodamura,

Iwate Prefecture is a prefecture of Japan located in the Tōhoku region of Honshu. It is the second-largest Japanese prefecture at , with a population of 1,210,534 (as of October 1, 2020). Iwate Prefecture borders Aomori Prefecture to the north, Akita Prefectur ...

where Nodamura virus was first isolated from ''

Culex tritaeniorhynchus ''Culex (Culex) tritaeniorhynchus'' is a species of mosquito and is the main vector of the disease Japanese encephalitis. This mosquito is a native of northern Asia, and parts of Africa (northeast and sub-Saharan). Females target large animals f ...

'' mosquitoes.

Virology

Structure

The virus is not enveloped and has an icosahedral capsid (triangulation number = 3) ranging from 29 to 35 nm in diameter. The

capsid A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may ...

is constructed of 32 capsomers.

Genome

The genome is linear, positive sense, bipartite (composed of two segments – RNA1 and RNA2) single stranded

RNA Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...

consisting of 4500

nucleotide Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules wi ...

s with a 5’ terminal

methylated In the chemical sciences, methylation denotes the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These t ...

cap and a non-polyadenylated 3’ terminal. RNA1, which is ~3.1 kilobases in length, encodes a protein that has multiple functional domains: a mitochondrial targeting domain, a transmembrane domain, an RNA-dependent RNA polymerase (RdRp) domain, a self-interaction domain and an RNA capping domain. In addition, RNA1 encodes a subgenomic RNA3 that encodes protein B2, an RNA silencing inhibitor. RNA2 encodes protein α, a viral capsid protein precursor, which is auto-cleaved into two mature proteins, a 38 kDa β protein and a 5 kDa γ protein, at a conserved Asn/

Ala Ala, ALA, Alaa or Alae may refer to: Places * Ala, Hiiu County, Estonia, a village * Ala, Valga County, Estonia, a village * Ala, Alappuzha, Kerala, India, a village * Ala, Iran, a village in Semnan Province * Ala, Gotland, Sweden * Alad, S ...

site during virus assembly.

Life cycle

Viral replication is cytoplasmic. Entry into the host cell is achieved by penetration into the host cell. Replication follows the positive stranded RNA virus replication model. Positive stranded RNA virus transcription, using the internal initiation model of subgenomic RNA transcription is the method of transcription. Vertebrates and invertebrates serve as the natural host. Transmission routes are contact and contamination.

Taxonomy

The members of the genus ''Alphanodavirus'' were originally isolated from insects while those of the genus ''Betanodavirus'' were isolated from fish. A small number of nodoviruses seem to lie outside either of these clades. '' Flock house virus'' (FHV) is the best studied of the nodaviruses. There are nine species in this family, assigned to two genera: * '' Alphanodavirus'' ** '' Black beetle virus'' ** '' Boolarra virus'' ** '' Flock House virus'' ** '' Nodamura virus'' ** '' Pariacoto virus'' * '' Betanodavirus'' ** '' Barfin flounder nervous necrosis virus'' ** '' Redspotted grouper nervous necrosis virus'' ** '' Striped jack nervous necrosis virus'' ** '' Tiger puffer nervous necrosis virus''

References

External links

ICTV Report: ''Nodaviridae''

{{Taxonbar, from=Q3772908 Virus families Fish viral diseases Insect viral diseases Riboviria