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a group of single-strand RNA viruses with a protein coat

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/12/13 14:12:46」(JST)

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A picornavirus is a virus belonging to the family Picornaviridae. Picornaviruses are non-enveloped, positive-stranded RNA viruses with an icosahedral capsid. The genome RNA is unusual because it has a protein on the 5' end that is used as a primer for transcription by RNA polymerase. The name is derived from pico, meaning small, and RNA, referring to the ribonucleic acid genome, so "pico-rna-virus" literally means small RNA virus.

Picornaviruses are separated into a number of genera and include many important pathogens of humans and animals.^[1] The diseases they cause are varied, ranging from acute "common-cold"-like illnesses, to poliomyelitis, to chronic infections in livestock. Additional species not belonging to any of the recognised genera continue to be described.^[2]

Taxonomy[edit]

Picornaviruses are separated into a number of genera. Contained within the picornavirus family are many organisms of importance as vertebrate and human pathogens, shown in the table below.

Enteroviruses infect the enteric tract, which is reflected in their name. On the other hand, rhinoviruses infect primarily the nose and the throat. Enteroviruses replicate at 37°C, whereas rhinoviruses grow better at 33°C, as this is the lower temperature of the nose. Enteroviruses are stable under acid conditions and thus they are able to survive exposure to gastric acid. In contrast, rhinoviruses are acid-labile (inactivated or destroyed by low pH conditions) and that is the reason why rhinovirus infections are restricted to the nose and throat.

**Picornavirus Genera, Species and Serotypes**
Genus	Species (* signifies type species)	Serotypes
Aphthovirus	Bovine rhinitis A virus	2 types: bovine rhinitis A virus (BRAV) 1-2 (formerly bovine rhinovirus 1 & 3)
	Bovine rhinitis B virus	1 type: bovine rhinitis B virus (BRBV) 1 (formerly bovine rhinovirus 2)
	Equine rhinitis A virus	1 type: equine rhinitis A virus (ERAV) 1 (formerly equine rhinovirus 1)
	Foot-and-mouth disease virus^[3] *	7 types: O, A, C, Southern African Territories (SAT) 1, SAT 2, SAT 3 and Asia 1
Aquamavirus	Aquamavirus A	1 type: seal aquamavirus A1 (SeAV-A1)
Avihepatovirus	Duck hepatitis A virus	3 types: duck hepatitis A virus (DHAV) 1-3
Cardiovirus	Encephalomyocarditis virus *	2 types: encephalomyocarditis virus (EMCV) 1 & EMCV-2. Note: Columbia SK virus, Maus Elberfeld virus and Mengovirus are strains of EMCV-1.
Cardiovirus	Theilovirus	12 types: Theiler's murine encephalomyelitis virus (TMEV), Vilyuisk human encephalomyelitis virus (VHEV), Thera virus (TRV), Saffold virus (SAFV) 1-9
Cosavirus	Cosavirus A	24 types: cosavirus A1 (CoSV-A1) to CoSV-A24
Dicipivirus	Cadicivirus A	1 type: canine picodicistrovirus 1 (CaPdV-1)
Enterovirus	Enterovirus A (formerly Human enterovirus A)	23 types: coxsackievirus A2 (CV-A2), CV-A3, CV-A4, CV-A5, CV-A6, CV-A7, CV-A8, CV-A10, CV-A12, CV-A14, CV-A16, enterovirus (EV) A71, EV-A76, EV-A89, EV-A90, EV-A91, EV-A92, EV-114, EV-A119, SV19, SV43, SV46 & BA13; see also coxsackie A virus
	Enterovirus B (formerly Human enterovirus B)	60 types: coxsackievirus B1 (CV-B1), CV-B2, CV-B3, CV-B4, CV-B5 (incl. swine vesicular disease virus [SVDV]), CV-B6, CV-A9, echovirus 1 (E-1; incl. E-8), E-2, E-3, E-4, E-5, E-6, E-7, E-9 (incl. CV-A23), E-11, E-12, E-13, E-14, E-15, E-16, E-17, E-18, E-19, E-20, E-21, E-24, E-25, E-26, E-27, E-29, E-30, E-31, E-32, E-33, enterovirus B69 (EV-B69), EV-B73, EV-B74, EV-B75, EV-B77, EV-B78, EV-B79, EV-B80, EV-B81, EV-B82, EV-B83, EV-B84, EV-B85, EV-B86, EV-B87, EV-B88, EV-B93, EV-B97, EV-B98, EV-B100, EV-B101, EV-B106, EV-B107, EV-B110 & SA5; see also coxsackie B virus and echovirus
	Enterovirus C * (formerly Human enterovirus C)	23 types: poliovirus (PV) 1, PV-2, PV-3, coxsackievirus A1 (CV-A1), CV-A11, CV-A13, CV-A17, CV-A19, CV-A20, CV-A21, CV-A22, CV-A24, EV-C95, EV-C96, EV-C99, EV-C102, EV-C104, EV-C105, EV-C109, EV-C113, EV-C116, EV-C117 & EV-118
	Enterovirus D (formerly Human enterovirus D)	5 types: enterovirus D68 (EV-D68), EV-D70, EV-D94, EV-D111 & EV-D120
	Enterovirus E (formerly Bovine enterovirus group A)	4 types (proposed): enterovirus E1 (EV-E1), EV-E2, EV-E3 & EV-E4
	Enterovirus F (formerly Bovine enterovirus group B)	6 types (proposed): enterovirus F1 (EV-F1), EV-F2, EV-F3, EV-F4, EV-F5 & EV-E6
	Enterovirus G (formerly Porcine enterovirus B)	6 types: enterovirus (EV) G1 to G6 (formerly porcine enterovirus 9-10, 14-16 & ovine enterovirus 1)
	Enterovirus H (formerly Simian enterovirus A)	1 type: enterovirus H1 (EV-H1)
	Enterovirus J	6 types: simian virus 6 (SV6), enterovirus J103 (EV-J103), EV-J108, EV-J112, EV-J115 and EV-J121
	Rhinovirus A (formerly Human rhinovirus A)	77 types: human rhinovirus (HRV) A1, A2, A7, A8, A9, A10, A11, A12, A13, A15, A16, A18, A19, A20, A21, A22, A23, A24, A25, A28, A29, A30, A31, A32, A33, A34, A36, A38, A39, A40, A41, A43, A44, A45, A46, A47, A49, A50, A51, A53, A54, A55, A56, A57, A58, A59, A60, A61, A62, A63, A64, A65, A66, A67, A68, A71, A73, A74, A75, A76, A77, A78, A80, A81, A82, A85, A88, A89, A90, A94, A95, A96, A98, A100, A101, A102 and A103
	Rhinovirus B (formerly Human rhinovirus B)	25 types: human rhinovirus (HRV) B3, B4, B5, B6, B14, B17, B26, B27, B35, B37, B42, B48, B52, B69, B70, B72, B79, B83, B84, B86, B91, B92, B93, B97 and B99
	Rhinovirus C (formerly Human rhinovirus C)	51 types: human rhinovirus (HRV) C1-C51
Erbovirus	Equine rhinitis B virus *	3 types: equine rhinitis B virus (ERBV) 1-3 (formerly equine rhinovirus 2, 3 and acid-stable equine picornavirus)
Hepatovirus	Hepatitis A virus *	1 type: hepatitis A virus (HAV) 1
Kobuvirus	Aichivirus A * (formerly Aichi virus)	3 types: Aichi virus (AiV) 1, canine kobuvirus 1 (CaKV-1) & murine kobuvirus 1 (MuKV-1)
	Aichivirus B (formerly Bovine kobuvirus)	2 types: bovine kobuvirus (BKV) 1 & ovine kobuvirus 1 (OKV-1)
	Aichivirus C	1 type: porcine kobuvirus 1 (PKV-1)
Megrivirus	Melegrivirus A *	1 type: turkey hepatitis virus (THV) 1
Parechovirus	Human parechovirus *	14 types: human parechovirus (HPeV) 1-14
Parechovirus	Ljungan virus	4 types: Ljungan virus (LV) 1-4
Salivirus	Salivirus A	1 type: salivirus A1
Sapelovirus	Porcine sapelovirus * (formerly Porcine enterovirus A)	1 type: porcine sapelovirus (PSV) 1 (formerly PEV-8)
	Simian sapelovirus	3 types: simian sapleovirus (SSV) 1-3
	Avian sapelovirus	1 type: avian sapelovirus (ASV) 1
Senecavirus	Seneca Valley virus *	1 type: Seneca Valley virus (SVV) 1
Teschovirus	Porcine teschovirus *	13 types: porcine teschovirus (PTV) 1 to 13
Tremovirus	Avian encephalomyelitis virus	1 type: avian encephalomyelitis virus (AEV) 1

Plant picornaviruses[edit]

The plant picornaviruses have a number of properties that are distinct from the animal viruses. They have been classified into the family Secoviridae containing the subfamily Comovirinae (genera Comovirus, Fabavirus and Nepovirus), and genera Sequivirus, Waikavirus, Cheravirus, Sadwavirus and Torradovirus (type species Tomato torrado virus)).

Insect picornaviruses[edit]

A number of picorna like viruses have been described infecting insects. These include Perina nuda picorna-like virus of the tussock moth, infectious flacherie virus of the silkworm and Sacbrood virus of the honeybee,^[4] Plautia stali intestine virus^[5] kelp fly virus,^[6] Ectropis obliqua picorna-like virus,^[7] deformed wing virus,^[8] acute bee paralysis virus, Drosophila C virus, Rhopalosiphum padi virus, and Himetobi P virus.^[9] Several have been placed in a separate family - the Dicistroviridae. Others have been placed into a new family Iflaviridae. This family includes Infectious flacherie virus and SeIV-1 virus.^[10] Another virus is Nora virus from Drosophila melanogaster. This latter virus awaits further classification.

Virology[edit]

Picornaviruses are classed under Baltimore's viral classification system as group IV viruses as they contain a single stranded, positive sense RNA genome of between 7.2 and 9.0 kb (kilobases) in length. Like most positive sense RNA genomes, the genetic material alone is infectious; although substantially less virulent than if contained within the viral particle, the RNA can have increased infectivity when transfected into cells.

Structure[edit]

The capsid is an arrangement of 60 protomers in a tightly packed Icosahedral structure. Each protomer consists of 4 polypeptides known as VP (viral protein)1, 2, 3 and 4. VP2 and VP4 polypeptides originate from one protomer known as VP0 that is cleaved to give the different capsid components. The Icosahedral is said to have a triangulation number of 3, this means that in the icosahedral structure each of the 60 triangles that make up the capsid are split into 3 little triangles with a subunit on the corner. Depending on the type and degree of dehydration the viral particle is around 27-30 nm in diameter. The viral genome is around 2500 nm in length so we can therefore conclude that it must be tightly packaged within the capsid along with substances such as sodium ions in order to cancel out the negative charges on the RNA caused by the phosphate groups.

Genome[edit]

The genome itself is non-segmented and positive-sense (the same sense as mammalian mRNA, being read 5' to 3'). Unlike mammalian mRNA picornaviruses do not have a 5' cap but a virally encoded protein known as VPg. However, like mammalian mRNA, the genome does have a poly(A) tail at the 3' end. There is an un-translated region (UTR) at both ends of the picornavirus genome. The 5' UTR is usually longer, being around 500-1200 nucleotides (nt) in length, compared to that of the 3' UTR, which is around 30-650 nt. It is thought that the 5' UTR is important in translation and the 3' in negative strand synthesis; however the 5' end may also have a role to play in virulence of the virus. The rest of the genome encodes structural proteins at the 5' end and non-structural proteins at the 3' end in a single polyprotein.

The polyprotein is organised as follows: L-1ABCD-2ABC-3ABCD with each letter representing a protein, however, there are variations to this layout.

The 3B protein is the VPg protein. The 3D protein is the RNA polymerase.

Replication[edit]

The viral particle binds to cell surface receptors. This causes a conformational change in the viral capsid proteins, and myristic acid are released. These acids form a pore in the cell membrane through which RNA is injected [2]. Once inside the cell, the RNA un-coats and the (+) strand RNA genome is replicated through a double-stranded RNA intermediate that is formed using viral RDRP (RNA-Dependent RNA polymerase). Translation by host cell ribosomes is not initiated by a 5' G cap as usual, but rather is initiated by an IRES (Internal Ribosome Entry Site). The viral lifecycle is very rapid with the whole process of replication being completed on average within 8 hours. However as little as 30 minutes after initial infection, cell protein synthesis declines to almost zero output – essentially the macromolecular synthesis of cell proteins is “shut off”. Over the next 1–2 hours there is a loss of margination of chromatin and homogeneity in the nucleus, before the viral proteins start to be synthesized and a vacuole appears in the cytoplasm close to the nucleus that gradually starts to spread as the time after infection reaches around 3 hours. After this time the cell plasma membrane becomes permeable, at 4–6 hours the virus particles assemble, and can sometimes be seen in the cytoplasm. At around 8 hours the cell is effectively dead and lyses to release the viral particles.

Experimental data from single step growth-curve-like experiments have allowed scientists to look at the replication of the picornaviruses in great detail. The whole of replication occurs within the host cell cytoplasm and infection can even happen in cells that do not contain a nucleus (known as enucleated cells) and those treated with actinomycin D (this antibiotic would inhibit viral replication if this occurred in the nucleus.)

History[edit]

In 1897, foot-and-mouth disease virus (FMDV), the first animal virus, was discovered. FMDV is the prototypic member of the Aphthovirus genus in the Picornaviridae family.^[3] The plaque assay was developed using poliovirus. Both RNA dependent RNA polymerase and polyprotein synthesis were discovered by studying poliovirus infected cells.

References[edit]

^ Mettenleiter TC and Sobrino F (editors). (2008). Animal Viruses: Molecular Biology. Caister Academic Press. ISBN 978-1-904455-22-6. [1].
^ Lau SK, Woo PC, Lai KK, Huang Y, Yip CC, Shek CT, Lee P, Lam CS, Chan KH, Yuen KY (2011) Complete genome analysis of three novel picornaviruses from diverse bat species. J Virol.
^ ^a ^b Martinez-Salas et al. (2008). "Foot-and-Mouth Disease Virus". Animal Viruses: Molecular Biology. Caister Academic Press. isbn=978-1-904455-22-6.
^ Wu CY, Lo CF, Huang CJ, Yu HT, Wang CH (2002) The complete genome sequence of Perina nuda picorna-like virus, an insect-infecting RNA virus with a genome organization similar to that of the mammalian picornaviruses. Virology 294(2):312-323
^ Sasaki J, Nakashima N, Saito H, Noda H (1998) An insect picorna-like virus, Plautia stali intestine virus, has genes of capsid proteins in the 3' part of the genome. Virology 244(1):50-58
^ Hartley CJ, Greenwood DR, Gilbert RJ, Masoumi A, Gordon KH, Hanzlik TN, Fry EE, Stuart DI, Scotti PD (2005) Kelp fly virus: a novel group of insect picorna-like viruses as defined by genome sequence analysis and a distinctive virion structure. J Virol 79(21):13385-13398
^ Wang X, Zhang J, Lu J, Yi F, Liu C, Hu Y. Sequence analysis and genomic organization of a new insect picorna-like virus, Ectropis obliqua picorna-like virus, isolated from Ectropis obliqua. J Gen Virol 85(Pt 5):1145-1151
^ Mingxiao M, Ming L, Jian C, Song Y, Shude W, Pengfei L (2011) Molecular and biological characterization of Chinese sacbrood virus LN isolate. Comp Funct Genomics 2011:409386.
^ Govan VA, Leat N, Allsopp M, Davison S (2000) Analysis of the complete genome sequence of acute bee paralysis virus shows that it belongs to the novel group of insect-infecting RNA viruses. Virology 277(2):457-463
^ Millán-Leiva A, Jakubowska AK, Ferré J, Herrero S (2011) Genome sequence of SeIV-1, a novel virus from the Iflaviridae family infective to Spodoptera exigua. J Invertebr Pathol

Additional material

"Picornaviridae". Medical Subject Headings (MeSH). National Library of Medicine. Retrieved 2007-09-03.
"Picornavirus". The Pirbright Institute. Retrieved 2007-09-03.
Büchen-Osmond, C., ed. (2006). "ICTVdB - The Universal Virus Database, version 4". Columbia University, New York, USA.
Kahn, Cynthia M.; Line, Scott, eds. (2005-02-08). "Porcine Enteroviral Encephalomyelitis". The Merck Veterinary Manual (9th ed.). Merck. ISBN 0-911910-50-6

External links[edit]

ICTV International Committee on Taxonomy of Viruses Master Species List 2009 Version 4
ICTV International Committee on Taxonomy of Viruses (official site)
Picornaviruses - description, replication, disease
Picornaviruses in NCBI Taxonomy browser
Picornaviridae classification by the International Committee on Taxonomy of Viruses
Animal viruses
Viralzone: Picornaviridae
Virus Pathogen Database and Analysis Resource (ViPR): Picornaviridae

UpToDate Contents

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1. ライノウイルス感染の疫学、臨床症状、および病因 epidemiology clinical manifestations and pathogenesis of rhinovirus infections
2. エンテロウイルスおよびパレコウイルス感染症の疫学、病因、治療、および予防 epidemiology pathogenesis treatment and prevention of enterovirus and parechovirus infections
3. 小児における感冒：臨床的特徴および診断 the common cold in children clinical features and diagnosis
4. 致死的喘息リスクを有する患者の特定 identifying patients at risk for fatal asthma
5. 小児の喘鳴へのアプローチ approach to wheezing in children

English Journal

NMR elucidation of the role of Mg2+ in the structure and stability of the conserved RNA motifs of the EMCV IRES element.

Mohammed S, Phelan MM, Rasul U, Ramesh V.Author information School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom. vasudevan.ramesh@manchester.ac.uk.AbstractThe three dimensional solution structures of a highly conserved 16mer RNA, endowed with a classic 'GNRA' tetraloop motif, and a 17mer RNA containing a cytosine-rich heptaloop which is predicted to be a potential receptor for the former RNA, of the I-domain of Encephalomyocarditis virus IRES have been determined by NMR spectroscopy. As Mg2+ plays an important role in the activity of the IRES, the corresponding NMR structures of the Mg2+ bound RNA complexes have also been determined. These RNA NMR structures, 16mer (21 constraints per residue), 16mer RNA/Mg2+ (21 constraints per residue), 17mer (17 constraints per residue) and 17mer RNA/Mg2+ (16 constraints per residue), were calculated to a high degree of precision with low RMSDs and low clash scores represent, to the best our knowledge, the first structures of a type II picornavirus IRES. Conformational analysis of the average structure showed that the RNAs and their Mg2+ complexes adopt characteristic A-form helical structures, stabilised by canonical and non-canonical interactions in both the stem and loop regions. The GCGA tetraloop of the 16mer folds into a standard GNRA conformation, with the structural role of A550 being in the form of a G547.A550 sheared base-pair made up of two hydrogen bonds. Further, the previously uncharacterised AACCCCA heptaloop present in the 17mer forms a compact tertiary loop motif, held together by strong π-π interactions. Analysis of the NMR structures demonstrates that the role of Mg2+ is principally to confer enhanced stability to the RNAs whereby the tetra- and heptaloops can achieve optimum conformation for any RNA-RNA interactions which are crucial for understanding the structure-function relationship of the IRES.
Organic & biomolecular chemistry.Org Biomol Chem.2014 Jan 21. [Epub ahead of print]
The three dimensional solution structures of a highly conserved 16mer RNA, endowed with a classic 'GNRA' tetraloop motif, and a 17mer RNA containing a cytosine-rich heptaloop which is predicted to be a potential receptor for the former RNA, of the I-domain of Encephalomyocarditis virus IRES have bee
PMID 24448682

Differential cleavage of IRES trans-acting factors (ITAFs) in cells infected by human rhinovirus.

Chase AJ1, Semler BL2.Author information 1Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA.2Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA. Electronic address: blsemler@uci.edu.AbstractHuman rhinovirus (HRV) is a major causative agent of the common cold, and thus has several important health implications. As a member of the picornavirus family, HRV has a small genomic RNA that utilizes several host cell proteins for RNA replication. Host proteins poly(rC) binding protein 2 (PCBP2) and polypyrimidine tract binding protein (PTB) are cleaved by a viral proteinase during the course of infection by the related picornavirus, poliovirus. The cleavage of PCBP2 and PTB inhibits poliovirus translation and has been proposed to mediate a switch in poliovirus template usage from translation to RNA replication. HRV RNA replication also requires a switch in template usage from translation to RNA replication; however, the mechanism is not yet known. We demonstrate that PCBP2 and PTB are differentially cleaved during HRV infection in different cell lines, suggesting that HRV utilizes a mechanism distinct from PCBP2 or PTB cleavage to mediate a switch in template usage.
Virology.Virology.2014 Jan 20;449:35-44. doi: 10.1016/j.virol.2013.10.030. Epub 2013 Nov 21.
Human rhinovirus (HRV) is a major causative agent of the common cold, and thus has several important health implications. As a member of the picornavirus family, HRV has a small genomic RNA that utilizes several host cell proteins for RNA replication. Host proteins poly(rC) binding protein 2 (PCBP2)
PMID 24418535

Recombination strategies and evolutionary dynamics of the human enterovirus A global gene pool.

Lukashev AN, Shumilina EY, Belalov IS, Ivanova OE, Eremeeva TP, Reznik VI, Trotsenko OE, Drexler JF, Drosten C.Author information Chumakov Institute of Poliomyelitis and Viral Encephalitides;AbstractWe analyzed natural recombination in 79 HEV-A strains representing 13 serotypes by sequencing of VP1, 2C, and 3D genome regions. The half-life of a non-recombinant tree node in coxsackieviruses 2, 4 and 10 was only 3.5 years, and never more than 9 years. All coxsackieviruses that differed by more than 7% of the nucleotide sequence in any genome region were recombinants relative to each other. Enterovirus 71, on the contrary, displayed remarkable genetic stability. Three major EV71 clades were stable for 19-29 years, with a half-life of non-recombinant viruses between 13 and 18.5 years in different clades. Only five EV71 strains out of over 150 recently acquired non-structural genome regions from coxsackieviruses, while none of 80 contemporary coxsackieviruses had non-structural genes transferred from the three EV71 clades. In contrast to earlier observations, recombination between VP1 and 2C genome regions was not more frequent than between 2C and 3D regions.
The Journal of general virology.J Gen Virol.2014 Jan 14. doi: 10.1099/vir.0.060004-0. [Epub ahead of print]
We analyzed natural recombination in 79 HEV-A strains representing 13 serotypes by sequencing of VP1, 2C, and 3D genome regions. The half-life of a non-recombinant tree node in coxsackieviruses 2, 4 and 10 was only 3.5 years, and never more than 9 years. All coxsackieviruses that differed by more th
PMID 24425417

Japanese Journal

ピコルナウイルスの感染初期過程 (特集 Positive Strand RNA Virusのウイルス学)

小池智
ウイルス 61(2), 183-191, 2011-12
NAID 40019176880

Real-time polymerase chain reaction as a rapid and efficient alternative to estimation of picornavirus titers by tissue culture infectious dose 50% or plaque forming units

JONSSON Nina,GUILBERG Maria,LINDBERG A. Michael
Microbiology and immunology 53(3), 149-154, 2009-03-20
NAID 10027685997

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「Picornaviridae」

Picornavirus
Virus classification
Group:	Group IV ((+)ssRNA)
Order:	Picornavirales
Family:	Picornaviridae
Genera
	Aphthovirus; Aquamavirus; Avihepatovirus; Cardiovirus; Cosavirus; Dicipivirus; Enterovirus; Erbovirus; Hepatovirus; Kobuvirus; Megrivirus; Parechovirus; Salivirus; Sapelovirus; Senecavirus; Teschovirus; Tremovirus;