Arterivirus

VIRION

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

Monopartite, linear, positive sense, ssRNA(+) genome of 12-16kb 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.

GENE EXPRESSION

The virion RNA is infectious and serves as both genome and viral messenger RNA. Genomic RNA encodes for ORF1a, and ORF1b is translated by a ribosomal frameshifting. Resulting proteins 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, LDV and SHFV also express a truncated polyprotein 1aTF due to a ribosomal frameshifting in the nsp2 gene.
The 3' proximal region of SHFV contains in addition a large insertion that may encode three additional glycoproteins.
The 3' proximal region of SHFV contains in addition a large insertion that may encode three additional glycoproteins.

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.

Host-virus interaction

Apoptosis modulation

The equine arteritis virus and PRRSV induce 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

16 entries grouped by strain (browse by keywords)

All proteins are shown (view only 10 complete proteome entries)

9 entries

Equine arteritis virus (strain Bucyrus) (EAV) reference strain

Select_allDeselect_all
GP3_EAVBU Glycoprotein 3 (Protein GP3)
E_EAVBU Envelope small membrane protein (Protein E) (Glycoprotein 2a) (Protein GP2a)
GP5_EAVBU Glycoprotein 5 (Protein GP5) (G(L))
GP4_EAVBU Glycoprotein 4 (Protein GP4)
GP2B_EAVBU Glycoprotein 2b (Protein GP2b) (GP(S))
M_EAVBU Membrane protein (Protein M)
NCAP_EAVBU Nucleoprotein (Nucleocapsid protein) (Protein N)
RPOA_EAVBU Replicase polyprotein 1ab (ORF1ab polyprotein) [Cleaved into: Nsp1 papain-like cysteine proteinase ...
ORF5A_EAVBU Protein ORF5a

1 entry

Simian hemorrhagic fever virus (SHFV) reference strain

RPOA_SHFV Replicase polyprotein 1ab (ORF1ab polyprotein) [Cleaved into: Nsp1-alpha papain-like cysteine ...

3 entries

Lactate dehydrogenase elevating virus (strain C) (LDV)

Select_allDeselect_all
NCAP_LDVC Nucleoprotein (Nucleocapsid protein) (Protein N)
RPOA_LDVC Replicase polyprotein 1ab (ORF1ab polyprotein) [Cleaved into: Nsp1-alpha papain-like cysteine ...
VPX_LDVC Protein X (Envelope protein) (VpX)

2 entries

Lactate dehydrogenase-elevating virus (LDV)

Select_allDeselect_all
NCAP_LDV Nucleoprotein (Nucleocapsid protein) (Protein N)
VPX_LDV Protein X (Envelope protein) (VpX)

1 entry

Lactate dehydrogenase elevating virus (strain Plagemann) (LDV)

RPOA_LDVP Replicase polyprotein 1ab (ORF1ab polyprotein) [Cleaved into: Nsp1-alpha papain-like cysteine ...