Picornaviridae

VIRION

Non-enveloped, spherical, about 30 nm in diameter, T=pseudo3 icosahedral capsid surrounding the naked RNA genome. The capsid consists of a densely-packed icosahedral arrangement of 60 protomers, each consisting of 4 polypeptides, VP1, VP2, VP3 and VP4. VP4 is located on the internal side of the capsid.

GENOME

Monopartite, linear ssRNA(+) genome of 7.1-8.9 kb, polyadenylated, composed of a single ORF encoding a polyprotein. Viral genomic RNA has a viral protein (VPg) at its 5' end instead of a methylated nucleotide cap structure. The long UTR at the 5' end contains an internal ribosome entry site (IRES). The P1 region encodes the structural polypeptides. The P2 and P3 regions encode the nonstructural proteins associated with replication. The shorter 3' UTR is important in (-)strand synthesis. L is an additional N-terminal leader protein present in some genera that can either be a papain-like cysteine proteinases (genera aphthovirus, erbovirus) or have another function (genera kobuvirus, cardiovirus, teschovirus, sapelovirus, senecavirus).

GENE EXPRESSION

The virion RNA is infectious and serves as both the genome and viral messenger RNA. The IRES allows direct translation of the polyprotein. The polyprotein is initially processed by the viral protease(s) into various precursor and mature proteins to yield the structural proteins, replicase, VPg, and a number of proteins that modify the host cell, ultimately leading to cell lysis.

REPLICATION

CYTOPLASMIC

  1. Attachement of the virus to host receptors mediates endocytosis of the virus into the host cell.
  2. The capsid undergoes a conformational change and releases VP4 that opens a pore in the host endosomal membrane and the viral genomic RNA penetrates into the host cell cytoplasm.
  3. VPg is removed from the viral RNA, which is then translated into a processed polyprotein.
  4. In entero-, rhino-, and aphthoviruses, shutoff of cellular cap-dependent translation through the cleavage of translation initiation factors by viral protease.
  5. Replication occurs in viral factories made of membrane vesicles derived from the ER. A dsRNA genome is synthesized from the genomic ssRNA(+).
  6. The dsRNA genome is transcribed/replicated thereby providing viral mRNAs/new ssRNA(+) genomes.
  7. New genomic RNA is believed to be packaged into preassembled procapsids.
  8. Cell lysis and virus release.
  9. Maturation of provirions by an unknown host protease.

Host-virus interaction

Apoptosis modulation

Picornaviruses modulate host apoptosis .

Poliovirus infection activates the apoptotic pathway, involving mitochondrial damage, cytochrome c efflux, and consecutive activation of caspases (caspase-3 caspase and -9) , whereas antiapoptotic activity has been attributed to cardiovirus leader protein .

Modulation of apoptosis depends on the host cell-type and on the time the infection because of the presence of viral pro- and anti-apoptotic factors respectively at the beginning and at the end of the infectious cycle .

Autophagy modulation

Picornaviruses subvert the cell autophagic pathway to facilitates viral infection :

- Human rhinovirus 2 and EMCV activates the autophagic pathway

- Foot-and-mouth disease virus utilizes the autophagic pathway

- Coxsackievirus and poliovirus infection induces autophagy-like vesicles

Innate immune response inhibition

Picornaviruses inhibit the host IFN-mediated response by inactivating either MDA-5, RIG-I, MAVS or IRF-3:

- HAV cleaves and inhibits MAVS

- Coxsackievirus B3 cleaves and inhibits MAVS

- Enteroviruses and cardiviruses cleave and inhibit RIG-I
-Poliovirus cleaves and inhibits MDA-5

- Mengovirus and foot-and-mouth disease virus leader proteins inhibit IRF-3 .

Picornaviruses inhibit Toll-like receptor 3 mediated antiviral response as well:

- Coxsackievirus B 3C, HAV and enterovirus 71 proteases 3C cleave TRIF .

Host gene expression shutoff by virus

Picornaviruses inhibit host translation by cleaving various translation factors such as PABP (FMDV, poliovirus and coxsackievirus) , eIF3a, eIF3b (FMDV) , eIF5B and activating 4E-BP1 .

Poliovirus also inhibits host transcription by cleaving the TATA-binding protein .

Some enteroviruses or cardioviruses inhibit host mRNA export as well.

Matching UniProtKB/Swiss-Prot entries

78 entries grouped by protein (browse by keywords)

3 entries

Protein 2B*

Select_allDeselect_all
ALT2B_EMCVR
Encephalomyocarditis virus (strain Rueckert) (EMCV) reference strain
ALT2B_EMCV
Encephalomyocarditis virus
ALT2B_ENMGO
Mengo encephalomyocarditis virus

74 entries

Genome polyprotein

Select_allDeselect_all
POLG_AEVCA
Avian encephalomyelitis virus (strain Calnek vaccine) (AEV) reference strain
POLG_EMCVR
Encephalomyocarditis virus (strain Rueckert) (EMCV) reference strain
POLG_HAVHM
Human hepatitis A virus genotype IB (isolate HM175) (HHAV) (Human hepatitis A virus (isolate Human/Australia/HM175/1976)) reference strain
POLG_HPE2W
Human parechovirus 2 (strain Williamson) (HPeV-2) (Echovirus 23) reference strain
POLG_HRV8A
Human rhinovirus A serotype 89 (strain 41467-Gallo) (HRV-89) reference strain
POLG_POL1M
Poliovirus type 1 (strain Mahoney) reference strain
POLG_AEVL2
Avian encephalomyelitis virus (strain L2Z) (AEV)
POLG_AEVVR
Avian encephalomyelitis virus (strain Van Reokel) (AEV)
POLG_BOVEV
Bovine enterovirus (strain VG-5-27) (BEV)
POLG_CX16G
Coxsackievirus A16 (strain G-10)
POLG_CX16T
Coxsackievirus A16 (strain Tainan/5079/98)
POLG_CXA21
Coxsackievirus A21 (strain Coe)
POLG_CXA24
Coxsackievirus A24 (strain EH24/70)
POLG_CXA9
Coxsackievirus A9 (strain Griggs)
POLG_CXB1J
Coxsackievirus B1 (strain Japan)
POLG_CXB2O
Coxsackievirus B2 (strain Ohio-1)
POLG_CXB3N
Coxsackievirus B3 (strain Nancy)
POLG_CXB3W
Coxsackievirus B3 (strain Woodruff)
POLG_CXB4E
Coxsackievirus B4 (strain E2)
POLG_CXB4J
Coxsackievirus B4 (strain JVB / Benschoten / New York/51)
POLG_CXB5P
Coxsackievirus B5 (strain Peterborough / 1954/UK/85)
POLG_CXB6S
Coxsackievirus B6 (strain Schmitt)
POLG_EC01F
Echovirus 1 (strain Human/Egypt/Farouk/1951) (E-1)
POLG_EC05N
Echovirus 5 (strain Noyce)
POLG_EC06C
Echovirus 6 (strain Charles)
POLG_EC09B
Echovirus 9 (strain Barty)
POLG_EC09H
Echovirus 9 (strain Hill)
POLG_EC11G
Echovirus 11 (strain Gregory)
POLG_EC12T
Echovirus 12 (strain Travis)
POLG_EC30B
Echovirus 30 (strain Bastianni)
POLG_EMCV
Encephalomyocarditis virus
POLG_EMCVB
Encephalomyocarditis virus (strain emc-b nondiabetogenic)
POLG_EMCVD
Encephalomyocarditis virus (strain emc-d diabetogenic)
POLG_ENMGO
Mengo encephalomyocarditis virus
POLG_FMDV1
Foot-and-mouth disease virus (strain A10-61) (Aphthovirus A) (FMDV)
POLG_FMDV5
Foot-and-mouth disease virus (isolate -/Germany/A5Westerwald/1951 serotype A) (FMDV)
POLG_FMDVA
Foot-and-mouth disease virus (isolate Bovine/United Kingdom/A12Valle119/1932 serotype A) (FMDV)
POLG_FMDVC
Foot-and-mouth disease virus (isolate Bovine/Brazil/A24Cruzeiro/1955 serotype A) (FMDV)
POLG_FMDVI
Foot-and-mouth disease virus (isolate -/Brazil/C3Indaial/1971 serotype C) (FMDV)
POLG_FMDVO
Foot-and-mouth disease virus (isolate Bovine/Germany/O1Kaufbeuren/1966 serotype O) (FMDV)
POLG_FMDVS
Foot-and-mouth disease virus (isolate -/Spain/S8c1SantaPau/1970 serotype C) (FMDV)
POLG_FMDVT
Foot-and-mouth disease virus (isolate -/Germany/C1Oberbayen/1960 serotype C) (FMDV)
POLG_FMDVZ
Foot-and-mouth disease virus (isolate -/Azerbaijan/A22-550/1965 serotype A) (FMDV)
POLG_HAV88
Human hepatitis A virus genotype IIB (isolate SLF88) (HHAV) (Human hepatitis A virus (isolate Human/Sierra Leone/SLF88/1988))
POLG_HAVCF
Human hepatitis A virus genotype IIA (isolate CF-53) (HHAV) (Human hepatitis A virus (isolate Human/France/CF-53/1979))
POLG_HAVGB
Human hepatitis A virus genotype IA (isolate GBM) (HHAV) (Human hepatitis A virus (isolate Human/Germany/GBM/1976))
POLG_HAVH2
Human hepatitis A virus genotype IA (isolate H2) (HHAV) (Human hepatitis A virus (isolate Human/China/H2/1982))
POLG_HAVJ8
Human hepatitis A virus genotype IIIB (isolate HAJ85-1) (HHAV) (Human hepatitis A virus (isolate Human/Japan/HAJ85-1/1985))
POLG_HAVLA
Human hepatitis A virus genotype IA (isolate LA) (HHAV) (Human hepatitis A virus (isolate Human/Northern California/LA/1974))
POLG_HAVMB
Human hepatitis A virus genotype IB (isolate MBB) (HHAV) (Human hepatitis A virus (isolate Human/Northern Africa/MBB/1978))
POLG_HAVNO
Human hepatitis A virus genotype IIIA (isolate NOR-21) (HHAV) (Human hepatitis A virus (isolate Human/Norway/NOR-21/1998))
POLG_HAVS2
Simian hepatitis A virus genotype V (isolate AGM-27) (SHAV) (Simian hepatitis A virus (isolate Cercopithecus/Kenya/AGM-27/1985))
POLG_HE701
Human enterovirus 70 (strain J670/71) (EV 70)
POLG_HE71B
Human enterovirus 71 (strain BrCr) (Ev 71)
POLG_HE71M
Human enterovirus 71 (strain 7423/MS/87) (Ev 71)
POLG_HPE1H
Human parechovirus 1 (strain Harris) (HPeV-1) (Echovirus 22)
POLG_HPE23
Human parechovirus 2 (strain CT86-6760) (HPeV-2) (Echovirus 23)
POLG_HRV14
Human rhinovirus 14 (HRV-14)
POLG_HRV16
Human rhinovirus 16 (HRV-16)
POLG_HRV1A
Human rhinovirus 1A (HRV-1A)
POLG_HRV1B
Human rhinovirus 1B (HRV-1B)
POLG_HRV2
Human rhinovirus 2 (HRV-2)
POLG_HRV3
Human rhinovirus 3 (HRV-3)
POLG_PEV9U
Porcine enterovirus 9 (strain UKG/410/73)
POLG_POL1S
Poliovirus type 1 (strain Sabin)
POLG_POL2L
Poliovirus type 2 (strain Lansing)
POLG_POL2W
Poliovirus type 2 (strain W-2)
POLG_POL32
Poliovirus type 3 (strain 23127)
POLG_POL3L
Poliovirus type 3 (strains P3/Leon/37 and P3/Leon 12A[1]B)
POLG_SVDVH
Swine vesicular disease virus (strain H/3 '76) (SVDV)
POLG_SVDVU
Swine vesicular disease virus (strain UKG/27/72) (SVDV)
POLG_TMEVB
Theiler's murine encephalomyelitis virus (strain BeAn 8386) (TMEV)
POLG_TMEVD
Theiler's murine encephalomyelitis virus (strain DA) (TMEV)
POLG_TMEVG
Theiler's murine encephalomyelitis virus (strain GDVII) (TMEV)

1 entry

Protein L*

SMALL_TMEVD
Theiler's murine encephalomyelitis virus (strain DA) (TMEV)