''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. A viral envelope protein or E protein is a protein in the env ...

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

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

encephalopathy Encephalopathy (; ) means any disorder or disease of the brain, especially chronic degenerative conditions. In modern usage, encephalopathy does not refer to a single disease, but rather to a syndrome of overall brain dysfunction; this syndrome ...

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 in ...

in fish. There are two genera in the family.

History

The name of the family is derived from the

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

ese village of Nodamura,

Iwate Prefecture is a Prefectures of Japan, prefecture of Japan located in the Tōhoku region of Honshu. It is the second-largest Japanese prefecture (behind Hokkaido) at , with a population of 1,165,886 (as of July 1, 2023). Iwate Prefecture borders Aomori Pre ...

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 animal ...

'' 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 m ...

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 that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyrib ...

consisting of 4500

nucleotide Nucleotides are Organic compound, organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both o ...

s with a 5’ terminal

methylated Methylation, in the chemical sciences, is 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 term ...

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 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.

References

External links

ICTV Report: ''Nodaviridae''

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