''Nodamura virus'' (NoV) is a member of the family
Nodaviridae
''Nodaviridae'' is a family of nonenveloped positive-strand RNA viruses. Vertebrates and invertebrates serve as natural hosts. Diseases associated with this family include: viral encephalopathy and retinopathy in fish. There are nine species in ...
, which was originally isolated from mosquitoes (''
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 ...
'') in Japan near the village of Nodamura in 1956.
Other members of Nodaviridae are flock house virus (FHV) and black beetle virus (BBV).
[Tesh, R. B.]
Infectivity and Pathogenicity of Nodamura Virus for Mosquitoes
" Journal of General . Virology 48.1 (1980): 177-82. Web. NoV has been found to multiply in several insect and tick species; however, these infected individuals seem to be
asymptomatic
In medicine, any disease is classified asymptomatic if a patient tests as carrier for a disease or infection but experiences no symptoms. Whenever a medical condition fails to show noticeable symptoms after a diagnosis it might be considered asy ...
. Nodamura virus is the only member of the genus
Alphanodavirus that can infect insects, fish, and mammals.
Taxonomy
Nodamura virus is a +
ssRNA
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 ...
virus. It is a member of the virus family Nodaviridae. Nodaviridae is made up of two
genera
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
,
Alphanodavirus and
Betanodavirus. NoV is a member of the Alphanodavirus. Other viruses in this genus are ''
Flock House virus'' and ''
Black beetle virus
''Black beetle virus'' (BBV) is a virus that was initially discovered in the North Island of New Zealand in Helensville in dead New Zealand black beetles (''Heteronychus arator'') in 1975.
History and general information
BBV is recognized as a ...
''.
["ViralZone]
Alphanodavirus
N.p., n.d. Web. 10 Dec. 2015.
Structure
The structure of nodamura virus is consistent with the structure of other viruses in the family Nodaviridae. These viruses contain a non-enveloped virion that has a diameter of approximately 30 nm. The virion is made up of 180 copies of a single viral
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 ...
protein.
The virion is organized in T=3
icosahedral symmetry
In mathematics, and especially in geometry, an object has icosahedral symmetry if it has the same symmetries as a regular icosahedron. Examples of other polyhedra with icosahedral symmetry include the regular dodecahedron (the dual of the ...
, which means there are 60 triangular subunits each made up of 3 viral capsid proteins. The virion contains both RNA1 and RNA2, but RNA3 is not included into the virion and is transcribed after infection of a host cell. RNA1 and RNA2 are required for successful infectivity of nodamura virus.
Genome
Nodamura virus capsid contains a segmented
RNA genome
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 carbohydr ...
made up of RNA1 and RNA2. RNA1 is responsible for encoding protein A, which is the RNA dependent RNA polymerase. RNA dependent
RNA polymerase
In molecular biology, RNA polymerase (abbreviated RNAP or RNApol), or more specifically DNA-directed/dependent RNA polymerase (DdRP), is an enzyme that synthesizes RNA from a DNA template.
Using the enzyme helicase, RNAP locally opens the ...
is necessary for replication of the nodamura virus genome. RNA1 is approximately 3.2 kb in length. RNA2 encodes the viral capsid protein, alpha. RNA2 is approximately 1.3 kb in length.
Nodamura virus RNA2, complete genome
/ref> RNA1's Protein A is also responsible for the synthesis of RNA3, which is synthesized from RNA1. In NoV, RNA3 is responsible for the translation of proteins B2-137, B2-134, and B1. Studies have shown that B2 proteins help to repress an antiviral response in nodamura infected cells.[Johnson, K. L., B. D. Price, L. D. Eckerle, and L. A. Ball. "Nodamura Virus Nonstructural Protein B2 Can Enhance Viral RNA Accumulation in Both Mammalian and Insect Cells." Journal of Virology 78.12 (2004): 6698-704. Web.]
Replication cycle
Entry
Virus penetrates into the host cell. Uncoating, and release of the viral genomic RNA into the cytoplasm. Specific mechanisms of viral attachment to host cell and entry
Entry may refer to:
*Entry, West Virginia, an unincorporated community in the United States
*Entry (cards), a term used in trick-taking card-games
*Entry (economics), a term in connection with markets
* ''Entry'' (film), a 2013 Indian Malayalam fil ...
into the host cell are currently unknown. No specific receptor has been identified.
Replication
Replication of Nodamura virus, a +ssRNA virus, occurs in the cytoplasm
In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The ...
of cells. Once the virus has entered the host cell, the virus is uncoated and the viral RNA is released into the cytoplasm.
The viral RNA-1 is then translated to produce the RdRp protein. Replication then begins in cytoplasmic viral factories. A dsRNA genome is synthesized from the genomic ssRNA(+) and further transcribed providing viral mRNAs/new ssRNA(+) genomes. The subgenomic RNA-3 is then transcribed along with the RNA-2, which encodes capsid protein alpha.
Assembly and release
Virus assembly in the cytoplasm around genomic RNA1 and RNA2. Assembled capsid protein alpha is cleaved into capsid protein beta and gamma. Release of infectious particles.
Modulation of host processes
The nodamura virus protein B2 (encoded by RNA3) has been shown to modulate the host process of antiviral response. B2 has been found to repress the host's antiviral response to allow the virus to successfully replicate.
Associated diseases
Since nodamura virus infects insects, fish, and mammals, there are different diseases caused in different species.Aedes albopictus
''Aedes albopictus'' (''Stegomyia albopicta''), from the mosquito (Culicidae) family, also known as the (Asian) tiger mosquito or forest mosquito, is a mosquito native to the tropical and subtropical areas of Southeast Asia. In the past few ce ...
'' and ''Toxorhynchites amboinensis'' mosquitoes, nodamura virus induced a loss of balance and an inability to fly. This was then followed by paralysis and death.
Tropism
Nodavirus has been found to successfully replicate in muscle cells and impair muscle fibrils causing paralysis
Paralysis (also known as plegia) is a loss of motor function in one or more muscles. Paralysis can also be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory damage. In the United States, roughly 1 in 50 ...
.
References
{{Taxonbar, from=Q18972045
Nodaviridae