Betaarterivirus (taxid:2499674)

VIRION

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Enveloped, spherical, about 45-60 nm in diameter. The virion is comprised of an isometric core of 20-30 nm surrounded by a lipid-containing envelope. The RNA genome associates with the N protein to form the nucleocapsid.

GENOME

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Monopartite, linear, ssRNA(+) genome of 14-16kb in size, capped, and polyadenylated. The leader RNA (65-89 bp) at the 5' end of the genome is also present at the end of each subgenomic RNAs.

Enzymes: EndoU ribonuclease

GENE EXPRESSION

The virion RNA is infectious and serves as both genome and viral messenger RNA. ORF1b is translated by a ribosomal frameshifting. Polyproteins pp1a and pp1ab are processed into the viral polymerase (RdRp) and other non-structural proteins involved in RNA synthesis. Structural proteins are expressed as subgenomic RNAs. The mRNA2 is bicistronic. PRRSV also expresses a truncated polyprotein 1aTF due to a ribosomal frameshifting in the nsp2 gene.
Protein GP2 and 5a are produced by leaky scanning from the E and gp5 subgenomic mRNA respectively.

ENZYMES

REPLICATION

CYTOPLASMIC

  1. Attachement to host receptors mediates clathrin-mediated endocytosis of the virus into the host cell.
  2. Fusion of virus membrane with the endosomal membrane. ssRNA(+) genome is released into the cytoplasm.
  3. Synthesis and proteolysis of replicase polyproteins.
  4. Replication occurs in viral factories. A dsRNA genome is synthesized from the genomic ssRNA(+).
  5. The dsRNA genome is transcribed/replicated thereby providing viral mRNAs/new ssRNA(+) genomes.
  6. Synthesis of structural proteins encoded by subgenomic mRNAs.
  7. assembly and ESCRT-independent budding at the membranes of endoplasmic reticulum (ER), intermediate compartments, and/or Golgi complex.
  8. Release of new virions by exocytosis.

Host-virus interaction

Apoptosis modulation

PRRSV induces apoptosis via host caspases activation (caspase-8 and mitochondria-dependent caspase-9)

Autophagy modulation

PRRSV induces autophagy to promote virus replication .

Innate immune response inhibition

PRRSV clearly inhibits the type-I IFN response and down-regulates TLR3, TLR7, and TLR8 expression.
At least three non-structural proteins (Nsp1, Nsp2, and Nsp11) play roles in the IFN suppression and NF-κB pathways :

Nsp1α subunit inhibits the IκB phosphorylation in the cytoplasm and therefore the activation of NF-κB.

Nsp1β inhibits phosphorylation of STAT1 and nuclear translocation of ISGF3 complex (composed of STAT1, STAT2 and IRF9). Nsp1β prevents IRF3 activation, thereby interfering with the RIG-I signaling pathway .

Nsp2 inhibits IFN production by blocking the ubiquitinylation of phosphorylated IκB and phosphorylation of IRF3 through the OTU domain. Nsp2 has the potential to deconjugate ISGylation.

Nsp11 suppresses IFN-β production through degradation of IPS-1 mRNA. For the second wave of IFN signaling, PRRSV Nsp1β blocks the phosphorylation of STATs and inhibits the nuclear translocation of ISGF3 complex (composed of STAT1, STAT2 and IRF9).

Matching UniProtKB/Swiss-Prot entries

(all links/actions below point to uniprot.org website)

24 entries grouped by strain

10 entries

Porcine reproductive and respiratory syndrome virus (strain Lelystad) (PRRSV) reference strain

Select_allDeselect_all
E_PRRSL Envelope small membrane protein (Protein E) (Glycoprotein 2b) (Protein GP2b) (Gs)
RPOTF_PRRSL Replicase polyprotein 1TF (ORF1ab polyprotein) [Cleaved into: Nsp1 (EC 3.4.22.-); Nsp1-alpha ...
RPOA_PRRSL Replicase polyprotein 1ab (ORF1ab polyprotein) [Cleaved into: Nsp1 (EC 3.4.22.-); Nsp1-alpha ...
NCAP_PRRSL Nucleoprotein (Nucleocapsid protein) (Protein N)
GP5_PRRSL Glycoprotein 5 (Protein GP5) (G(L))
M_PRRSL Membrane protein (Protein M)
GP2A_PRRSL Glycoprotein 2a (Protein GP2a) (GP2)
GP3_PRRSL Glycoprotein 3 (Protein GP3)
GP4_PRRSL Glycoprotein 4 (Protein GP4)
ORF5A_PRRSL Structural protein ORF5a

9 entries

Porcine reproductive and respiratory syndrome virus (isolate Pig/United States/SD 01-08/2001) (PRRSV)

Select_allDeselect_all
RPOA_PRRSS Replicase polyprotein 1ab (ORF1ab polyprotein) [Cleaved into: Nsp1 (EC 3.4.22.-); Nsp1-alpha ...
1ATF_PRRSS Truncated polyprotein 1aTF [Cleaved into: Nsp1 (EC 3.4.22.-); Nsp1-alpha papain-like cysteine ...
GP2A_PRRSS Glycoprotein 2a (Protein GP2a) (GP2)
E_PRRSS Envelope small membrane protein (Protein E) (Glycoprotein 2b) (Protein GP2b) (Gs)
GP4_PRRSS Glycoprotein 4 (Protein GP4)
GP3_PRRSS Glycoprotein 3 (Protein GP3)
GP5_PRRSS Glycoprotein 5 (Protein GP5) (G(L))
M_PRRSS Membrane protein (Protein M)
NCAP_PRRSS Nucleoprotein (Nucleocapsid protein) (Protein N)

2 entries

Porcine reproductive and respiratory syndrome virus (strain VR-2332) (PRRSV)

Select_allDeselect_all
RPOA_PRRSR Replicase polyprotein 1ab (ORF1ab polyprotein) [Cleaved into: Nsp1 (EC 3.4.22.-); Nsp1-alpha ...
ORF5A_PRRSR Structural protein ORF5a

1 entry

Porcine reproductive and respiratory syndrome virus (PRRSV)

RPOA_PRRSV Replicase polyprotein 1ab (ORF1ab polyprotein) [Cleaved into: Nsp1 (EC 3.4.22.-); Nsp1-alpha ...

1 entry

Porcine reproductive and respiratory syndrome virus (strain 16244B) (PRRSV)

RPOA_PRRS1 Replicase polyprotein 1ab (ORF1ab polyprotein) [Cleaved into: Nsp1 (EC 3.4.22.-); Nsp1-alpha ...

1 entry

Porcine reproductive and respiratory syndrome virus (strain HB-1) (PRRSV)

RPOA_PRRSB Replicase polyprotein 1ab (ORF1ab polyprotein) [Cleaved into: Nsp1 (EC 3.4.22.-); Nsp1-alpha ...