Betanodavirus | |
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Electron micrographs of grouper nervous necrosis virus particles | |
Virus classification | |
(unranked): | Virus |
Realm: | Riboviria |
Kingdom: | Orthornavirae |
Phylum: | Kitrinoviricota |
Class: | Magsaviricetes |
Order: | Nodamuvirales |
Family: | Nodaviridae |
Genus: | Betanodavirus |
Betanodavirus, or nervous necrosis virus (NNV), is a genus of nonenveloped positive-strand RNA viruses in the family Nodaviridae. [1] Member viruses infect fish and cause viral nervous necrosis (VNN) and viral encephalopathy and retinopathy (VER). [2] The genus contains four species. [3]
Betanodaviruses were first reported between 1989 and 1991. They were linked with high mortality rates in young fish and were initially described as a picornavirus-like virus. They were discovered around the same time in Australia, Norway, France and Japan. [4] [5] [6] [7] The oldest evidence related to the virus, however, dates back to 1984 in Queensland (Australia) where a disease outbreak with the clinical signs and histopathological lesions corresponding to NNV was reported. [8]
Viruses in the genus Betanodavirus are non-enveloped, with icosahedral geometries and T=3 symmetry. [2] The diameter is around 37 nm. The virus-like particle contains 180 subunits of the capsid protein, and each capsid protein (CP) shows three major domains: (i) the N-terminal arm, an inter-subunit extension at the inner surface; (ii) the shell domain (S-domain), a jelly-roll structure; and (iii) the protrusion domain (P-domain) formed by three-fold trimeric protrusions. [9]
Genomes are linear, segmented, bipartite, and around 21.4kb in total length. [2] The genome is split in two segments RNA1 and RNA2 that together encode three genes. [4]
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. Fish serve as the natural host. Transmission routes are passive diffusion and contact. [2]
Betanodaviruses affect teleost fish. A number of species are reported susceptible, more than 40 species, most of them marine. Transmission routes are passive diffusion and contact. [2] The disease is more likely to occur in larvae or juveniles but it can also affect adults. [10]
Viral nervous necrosis can have a clinical or sub-clinical presentation. Signs include: abnormal behaviour like lethargy, anorexia, spiral swimming; and change in pigmentation. Mortalities of affected populations can be of up to 100%. [11] Microscopical lesions are mostly located in brain, retina and spinal cord where necrosis of the neurons and the presence of round empty spaces called vacoules are commonly associated with the disease.[ citation needed ]
The most recent common ancestor of the four extant genotypes has been dated to ~1300 CE. [12] An early reassortment event appears to have occurred in the early 1980s in Southern Europe.[ citation needed ]
The following species are recognized: [13]
An RNA virus is a virus—other than a retrovirus—that has ribonucleic acid (RNA) as its genetic material. The nucleic acid is usually single-stranded RNA (ssRNA) but it may be double-stranded (dsRNA). Notable human diseases caused by RNA viruses include the common cold, influenza, SARS, MERS, COVID-19, Dengue virus, hepatitis C, hepatitis E, West Nile fever, Ebola virus disease, rabies, polio, mumps, and measles.
Picornaviruses are a group of related nonenveloped RNA viruses which infect vertebrates including fish, mammals, and birds. They are viruses that represent a large family of small, positive-sense, single-stranded RNA viruses with a 30 nm icosahedral capsid. The viruses in this family can cause a range of diseases including the common cold, poliomyelitis, meningitis, hepatitis, and paralysis.
Birnaviridae is a family of double-stranded RNA viruses. Salmonid fish, birds and insects serve as natural hosts. There are currently 11 species in this family, divided among seven genera. Diseases associated with this family include infectious pancreatic necrosis in salmonid fish, which causes significant losses to the aquaculture industry, with chronic infection in adult salmonid fish and acute viral disease in young salmonid fish.
The Caliciviridae are a family of "small round structured" viruses, members of Class IV of the Baltimore scheme. Caliciviridae bear resemblance to enlarged picornavirus and was formerly a separate genus within the picornaviridae. They are positive-sense, single-stranded RNA which is not segmented. Thirteen species are placed in this family, divided among eleven genera. Diseases associated with this family include feline calicivirus, rabbit hemorrhagic disease virus, and Norwalk group of viruses (gastroenteritis). Caliciviruses naturally infect vertebrates, and have been found in a number of organisms such as humans, cattle, pigs, cats, chickens, reptiles, dolphins and amphibians. The caliciviruses have a simple construction and are not enveloped. The capsid appears hexagonal/spherical and has icosahedral symmetry with a diameter of 35–39 nm.
Dicistroviridae is a family of viruses in the order Picornavirales. Invertebrates, including aphids, leafhoppers, flies, bees, ants, and silkworms, serve as natural hosts. There are 15 species in this family, assigned to three genera. Diseases associated with this family include: DCV: increased reproductive potential. extremely pathogenic when injected with high associated mortality. CrPV: paralysis and death.
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 the family, assigned to two genera.
White spot syndrome (WSS) is a viral infection of penaeid shrimp. The disease is highly lethal and contagious, killing shrimp quickly. Outbreaks of this disease have wiped out the entire populations of many shrimp farms within a few days, in places throughout the world.
Aphthovirus is a viral genus of the family Picornaviridae. Aphthoviruses infect split-hooved animals, and include the causative agent of foot-and-mouth disease, Foot-and-mouth disease virus (FMDV). There are seven FMDV serotypes: A, O, C, SAT 1, SAT 2, SAT 3 and Asia 1, and four non-FMDV serotypes belonging to three additional species Bovine rhinitis A virus (BRAV), Bovine rhinitis B virus (BRBV) and Equine rhinitis A virus (ERAV).
The white trevally, also known as striped jack,) is a jack of the family Carangidae widespread in tropical and warm temperate areas between 40°N and 47°S, in the Atlantic, Mediterranean, Indian, and Pacific Oceans. It has a deep body and a greenish colour with metallic overtones and a dark spot above the gills. The fins are yellow. Trevally are strong fighters and the flesh is good to eat if a little dry. It is often used as cut bait. Its maximum size is about 120 cm (47 in).
Marnaviridae is a family of positive-stranded RNA viruses in the order Picornavirales that infect various photosynthetic marine protists. Members of the family have non-enveloped, icosahedral capsids. Replication occurs in the cytoplasm and causes lysis of the host cell. The first species of this family that was isolated is Heterosigma akashiwo RNA virus (HaRNAV) in the genus Marnavirus, which infects the toxic bloom-forming Raphidophyte alga, Heterosigma akashiwo. As of 2021, there are twenty species across seven genera in this family, as well as many other related virus sequences discovered through metagenomic sequencing that are currently unclassified.
Enterovirus E is a picornavirus of the genus Enterovirus. The virus may also be referred to as enteric cytopathic bovine orphan virus (ECBO). It is endemic in cattle populations worldwide, and although normally fairly nonpathogenic, it can cause reproductive, respiratory, or enteric disease – particularly when the animal is concurrently infected with another pathogen.
Ranavirus is a genus of viruses in the family Iridoviridae. There are six other genera of viruses within the family Iridoviridae, but Ranavirus is the only one that includes viruses that are infectious to amphibians and reptiles. Additionally, it is one of the three genera within this family which infect teleost fishes, along with Lymphocystivirus and Megalocytivirus.
Picornavirales is an order of viruses with vertebrate, invertebrate, protist and plant hosts. The name has a dual etymology. First, picorna- is an acronym for poliovirus, insensitivity to ether, coxsackievirus, orphan virus, rhinovirus, and ribonucleic acid. Secondly, pico-, meaning extremely small, combines with RNA to describe these very small RNA viruses. The order comprises viruses that historically are referred to as picorna-like viruses.
Megalocytivirus is a genus of viruses in the family Iridoviridae and one of three genera within this family which infect teleost fishes, along with Lymphocystivirus and Ranavirus. Megalocytiviruses are an emerging group of closely related dsDNA viruses which cause systemic infections in a wide variety of wild and cultured fresh and saltwater fishes. Megalocytivirus outbreaks are of considerable economic importance in aquaculture, as epizootics can result in moderate fish loss or mass mortality events of cultured fishes.
Infectious pancreatic necrosis virus (IPNV) is a double-stranded RNA virus from the family Birnaviridae, in the genus Aquabirnavirus. Causing the highly infectious disease Infectious pancreatic necrosis, the virus primarily affects young salmonids resulting in high mortality, occasionally surpassing 90 percent in the early stages. IPNV or IPNV-like viruses have been isolated worldwide from at least 32 families of saltwater and freshwater salmonids and non-salmonids fish including salmon, flatfish, pike, eels and others. Other aquatic organisms infected include 11 molluscs and 4 species of crustaceans. Due to its wide host range and high mortality, the virus is of great concern to global aquaculture. In addition to persistence in hosts, IPNV is also perpetual in the environment, surviving across a range of conditions and capable of infecting fish with as little as 101TCID50/ml of the virus. Found in Europe, North America, South America, Africa, Asia, and Australia, the virus has led to significant losses in the mariculture of Atlantic salmon, brook trout, and rainbow trout.
Alphanodavirus is a genus of non-enveloped positive-strand RNA viruses in the family Nodaviridae. Insects, mammals, and fishes serve as natural hosts. Diseases associated with this genus include: Nodamura virus paralysis in infected wax moth larvae. Member viruses can also provoke paralysis and death to suckling mice and suckling hamsters. There are five species in this genus.
Aquabirnavirus is a genus of viruses, in the family Birnaviridae. Salmonid fish serve as natural hosts. There are three species in this genus. A disease associated with this genus, Infectious pancreatic necrosis (IPN) in salmonid fish, causes significant losses to the aquaculture industry. Chronic infection in adults, and acute viral disease in young salmonid fish can occur.
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