Coxsackie B4 virus | |
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Virus classification | |
(unranked): | Virus |
Realm: | Riboviria |
Kingdom: | Orthornavirae |
Phylum: | Pisuviricota |
Class: | Pisoniviricetes |
Order: | Picornavirales |
Family: | Picornaviridae |
Genus: | Enterovirus |
Species: | |
Virus: | Coxsackie B4 virus |
Coxsackie B4 virus are enteroviruses that belong to the Picornaviridae family. These viruses can be found worldwide. They are positive-sense, single-stranded, non-enveloped RNA viruses with icosahedral geometry. Coxsackieviruses have two groups, A and B, each associated with different diseases. Coxsackievirus group A is known for causing hand-foot-and-mouth diseases while Group B, which contains six serotypes, can cause a varying range of symptoms like gastrointestinal distress myocarditis. Coxsackievirus B4 has a cell tropism for natural killer cells and pancreatic islet cells. Infection can lead to beta cell apoptosis which increases the risk of insulitis. [1]
Coxsackievirus B4 is one of the six serotypes found in Group B and is a positive sense, single-stranded, non-enveloped RNA virus. Its genome is linear and is 7,293 nucleotides in length with both a 5’ and 3’ untranslated region and encodes its own 3’ poly-A tail. The 5’ untranslated region contains an internal ribosomal entry site (Type I IRES). Covalently bonded to the 5’ UTR is the viral protein VPg which aids in viral entry and replication. 2A and 3C are viral proteinases which aid in the cleavage of the polyprotein encoded for by the genome. 3D is the RNA-dependent RNA polymerase (RdRP). 2B, 2C, and 3A are core viral proteins. The genome also codes for 4 capsid proteins, VP4, VP1, VP2, and VP3 that form an icosahedral capsid for the viral particles that is about 30 nm. VP1-VP3 are responsible for the outer surface of the virion, while VP4 is imbedded within the capsid. [2] Altogether, the polyprotein encoded for by the coxsackievirus genome is almost 2,200 amino acids in length, and is eventually cleaved by the 2A and 3C proteinases as well as by host cell proteinases.
As Coxsackievirus B4, and all other members of the picornavirus family, are non-enveloped, they are notably resilient to disinfectants, solvents, low pH levels (i.e. stomach acid), low temperatures, and 70% alcohol.
The capsid of Coxsackie viruses have a distinguishable depression around the fivefold axis, termed the “canyon.” The canyon is thought to help with viral attachment through the interaction with cell surface molecules. (Riabi, 2014) When VP1 binds to the Coxsackie-Adenovirus receptor (CAR), which can be found on heart muscle cells as well as epithelial and endothelial cells, [3] a conformational change causes the host cell receptors to form a pore in the plasma membrane through which the VPg-linked viral genome could enter the cell. [2] Uncoating is unnecessary as it leaves the capsid at the plasma membrane and the genome is simply injected into the cytoplasm.
For positive sense, single-stranded RNA viruses, translation occurs before transcription. Upon entry of the genome into the cytoplasm of the host cell, the IRES in the 5’ UTR recruits ribosomal subunits (cap-independent mechanism) which starts the translation process. Once the polypeptide is completely translated, viral proteinases 2A and 3C, as well as cellular proteinases, cleave the polyprotein into individual proteins that will help continue the viral replication process. [4]
As soon as viral proteins have been translated and cleaved, negative sense transcripts of the viral genome are made to serve as a template for more positive-sense viral genome transcripts (which also serves as mRNA which can also be translated into more viral proteins). The viral genome encodes for a poly-A tail, which can be recognized by cellular initiation factors and ribosomal subunits which kick starts the transcription process to make the negative-sense strand, forming a double-stranded RNA intermediate [5]
Upon transcription of the negative sense RNA, it needs to get primed in order to start making more positive sense RNA genome. The VPg protein that is covalently linked to the 5’ end of the RNA genome has 2 U’s attached to it. The purpose of these U’s is to modify the VPg protein which serves as a protein primer which the viral RdRP can recognize and start forming more genome from the negative-sense. [5]
The viral protein 2C brings positive sense RNA genomes to the endoplasmic reticulum where assembly and maturation will occur. [4]
While all of this is occurring, viral proteinases are working to turn off host cell protein synthesis by cleaving the eIF-4 initiation factor. This process accomplishes the inhibition of ribosomes binding to host cell mRNAs. This effectively shuts down cap-dependent translation in the host cell. [4]
Once viral genome and viral proteins reach high enough concentrations within the host cell, structural proteins must assemble. The final step in maturation of the virus is when VP0, a precursor protein, is cleaved into VP2 and VP4. Viral capsid proteins come together to form pentamers, 12 of which come together to form an empty capsid, or procapsid (Expasy, Hunt, 2010). As mentioned before, the viral protein 2C brings CB4 viral genome to the endoplasmic reticulum where vesicle formation begins. The ER membrane moves to surround the genome and proteins, at which point the procapsid attaches to the exterior of the vesicle and encapsidates the genome and proteins. It is at this point that VP0 gets cleaved by a cellular proteinase and the virus finally becomes fully mature and infectious. Since CB4 is a non-enveloped virus, it accomplishes egress through cytolysis, breaking through the plasma membrane in order to move on to infect other cells in the host (Hunt, 2010)
Coxsackie B 1–4 viruses are typically the most severe and fatal neonatal diseases. Common symptoms can include myocarditis, meningoencephalitis, and hepatitis. Other less severe symptoms can include pneumonia, Gastrointestinal symptoms, pancreatitis, and seizures. Patients with Coxsackie B4 virus have seemed to have herpangina, tonsillitis, and pharyngitis. [6]
CB4 virus has caused transplacental infections in mice. Infection in the first couple weeks of gestation has been shown to be harmful for dams as well as the fetus, causing reduced litter sizes, abortion, or stillbirth. Pups that were born from dams infected on days 4 and 17 of gestation had significantly (p < 0.05) greater pancreatic abnormalities leading to symptoms similar to diabetes. [7]
One theory proposes that type 1 diabetes is a virus-triggered autoimmune response in which the immune system attacks virus-infected cells along with the beta cells in the pancreas, [8] [9] but to date there is no stringent evidence to support this hypothesis in humans. [10]
A 2004 systematic review analyzing a possible association between coxsackievirus B infection and type 1 diabetes was inconclusive. [11] A 2011 systematic review and meta-analysis showed an association between enterovirus infections and type 1 diabetes, but in contrast, other studies have shown that rather than triggering an autoimmune process, enterovirus infections, as coxsackievirus B, could protect against onset and development of type 1 diabetes. [12]
Enteroviruses commonly infect neonates and infants younger than 12 months. Coxsackie b viruses are usually spread to infants through perinatal transmission. However, more severe cases of coxsackie B viruses are spread through transplacental transmission. Common symptoms of neonatal coxsackie B virus infection in children include meningitis and/or encephalitis. Coxsackie B4 virus is able to infect the brain and spinal cord and cause inflammation. [6]
Infection due to Coxsackie B viruses can be determined by measuring the amount of neutralizing antibodies in the blood, PCR, and through microscopic detection. It is difficult to diagnose CBV based on the symptoms. [13]
Coxsackie A virus (CAV) is a cytolytic Coxsackievirus of the Picornaviridae family, an enterovirus.
The rhinovirus is the most common viral infectious agent in humans and is the predominant cause of the common cold. Rhinovirus infection proliferates in temperatures of 33–35 °C (91–95 °F), the temperatures found in the nose. Rhinoviruses belong to the genus Enterovirus in the family Picornaviridae.
Coxsackieviruses are a few related enteroviruses that belong to the Picornaviridae family of nonenveloped, linear, positive-sense single-stranded RNA viruses, as well as its genus Enterovirus, which also includes poliovirus and echovirus. Enteroviruses are among the most common and important human pathogens, and ordinarily its members are transmitted by the fecal–oral route. Coxsackieviruses share many characteristics with poliovirus. With control of poliovirus infections in much of the world, more attention has been focused on understanding the nonpolio enteroviruses such as coxsackievirus.
Coxsackie B is a group of six serotypes of coxsackievirus (CVB1-CVB6), a pathogenic enterovirus, that trigger illness ranging from gastrointestinal distress to full-fledged pericarditis and myocarditis.
Poliovirus, the causative agent of polio, is a serotype of the species Enterovirus C, in the family of Picornaviridae. There are three poliovirus serotypes: types 1, 2, and 3.
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.
Enterovirus is a genus of positive-sense single-stranded RNA viruses associated with several human and mammalian diseases. Enteroviruses are named by their transmission-route through the intestine.
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).
Drosophila X virus (DXV) belongs to the Birnaviridae family of viruses. Birnaviridae currently consists of three genera. The first genus is Entomobirnavirus, which contains DXV. The next genus is Aquabirnavirus, containing infectious pancreatic necrosis virus (IPNV). The last genus is Avibirnavirus, which contains infectious bursal disease virus (IBDV). All of these genera contain homology in three specific areas of their transcripts. The homology comes from the amino and carboxyl regions of preVP2, a small 21-residue-long domain near the carboxyl terminal of VP3, and similar small ORFs sequences.
Deformed wing virus (DWV) is an RNA virus, one of 22 known viruses affecting honey bees. While most commonly infecting the honey bee, Apis mellifera, it has also been documented in other bee species, like Bombus terrestris, thus, indicating it may have a wider host specificity than previously anticipated. The virus was first isolated from a sample of symptomatic honeybees from Japan in the early 1980s and is currently distributed worldwide. It is found also in pollen baskets and commercially reared bumblebees. Its main vector in A. mellifera is the Varroa mite. It is named after what is usually the most obvious deformity it induces in the development of a honeybee pupa, which is shrunken and deformed wings, but other developmental deformities are often present.
Erbovirus is a genus of viruses in the order Picornavirales, in the family Picornaviridae. Horses serve as natural hosts. There is only one species in this genus: Erbovirus A. Diseases associated with this genus include: upper respiratory tract disease with viremia and fecal shedding. Viruses belonging to the genus Erbovirus have been isolated in horses with acute upper febrile respiratory disease. The structure of the Erbovirus virion is icosahedral, having a diameter of 27–30 nm.
Pleconaril (Picovir) is an antiviral drug that was being developed by Schering-Plough for prevention of asthma exacerbations and common cold symptoms in patients exposed to picornavirus respiratory infections. Pleconaril, administered either orally or intranasally, is active against viruses in the Picornaviridae family, including Enterovirus and Rhinovirus. It has shown useful activity against the dangerous enterovirus D68.
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.
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.
sCAR-Fc is an experimental prophylactic treatment against coxsackievirus B3 (CVB) infections. Coxsackievirus B3 can cause cardiac damage, eventually resulting in a weakened and enlarged heart that is termed dilated cardiomyopathy. While many other treatments inhibit viral proliferation in myocytes, sCAR-Fc prevents the virus entering the cell by competitively binding to coxsackie virus and adenovirus receptors (CAR) on the membrane of myocytes.
Picornain 3C is a protease found in picornaviruses, which cleaves peptide bonds of non-terminal sequences. Picornain 3C’s endopeptidase activity is primarily responsible for the catalytic process of selectively cleaving Gln-Gly bonds in the polyprotein of poliovirus and with substitution of Glu for Gln, and Ser or Thr for Gly in other picornaviruses. Picornain 3C are cysteine proteases related by amino acid sequence to trypsin-like serine proteases. Picornain 3C is encoded by enteroviruses, rhinoviruses, aphtoviruses and cardioviruses. These genera of picoviruses cause a wide range of infections in humans and mammals.
Aichivirus A formerly Aichi virus (AiV) belongs to the genus Kobuvirus in the family Picornaviridae. Six species are apart of the genus Kobuvirus, Aichivirus A-F. Within Aichivirus A, there are six different types including human Aichi virus, canine kobuvirus, murine kobuvirus, Kathmandu sewage kobuvirus, roller kobuvirus, and feline kobuvirus.Three different genotypes are found in human Aichi virus, represented as genotype A, B, and C.
Avibirnavirus is a genus of viruses in family Birnaviridae. There is a single species in this genus: Infectious bursal disease virus, which infects chickens and other fowl. It causes severe inflammation of the bursa of Fabricius, and causes considerable morbidity and mortality.
Triatoma virus (TrV) is a virus belonging to the insect virus family Dicistroviridae. Within this family, there are currently 3 genera and 15 species of virus. Triatoma virus belongs to the genus Cripavirus. It is non-enveloped and its genetic material is positive-sense, single-stranded RNA. The natural hosts of triatoma virus are invertebrates. TrV is a known pathogen to Triatoma infestans, the major vector of Chagas disease in Argentina which makes triatoma virus a major candidate for biological vector control as opposed to chemical insecticides. Triatoma virus was first discovered in 1984 when a survey of pathogens of triatomes was conducted in the hopes of finding potential biological control methods for T. infestans.
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