Torovirus

VIRION

Enveloped, spherical, about 120 to 140nm in diameter. The tubular nucleocapsid is bend into an open torus hence the name “torovirus”.

GENOME

Monopartite, linear ssRNA(+) genome of 28kb in size. Capped, and polyadenylated.

GENE EXPRESSION

The virion RNA is infectious and serves as both the genome and viral messenger RNA. Genomic RNA encodes for ORF1a, as for ORF1b, it is translated by 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. Each RNA (genomic and subgenomic) is translated to yield only the protein encoded by the 5'-most ORF.
A putative 30K protein overlapping ORF1a might be expressed from an alternative CUG codon .

REPLICATION

CYTOPLASMIC

  1. Attachement of the viral S protein (maybe also HE if present) to host receptors mediates endocytosis of the virus into the host cell.
  2. Synthesis and proteolytic cleavage of the replicase polyprotein.
  3. Fusion of virus membrane with the endosomal membrane (probably mediated by E2), ssRNA(+) genome is released into the cytoplasm.
  4. Synthesis and proteolytic cleavage of the replicase polyprotein.
  5. Replication occurs in viral factories. A dsRNA genome is synthesized from the genomic ssRNA(+).
  6. The dsRNA genome is transcribed/replicated thereby providing viral mRNAs/new ssRNA(+) genomes.
  7. Synthesis of structural proteins encoded by subgenomic mRNAs.
  8. Assembly and budding at membranes of the endoplasmic reticulum (ER), the intermediate compartments, and/or the Golgi complex.
  9. Release of new virions by exocytosis.

Host-virus interaction

Apoptosis modulation

Equine torovirus Berne virus induces apoptosis in infected cells at late times postinfection via host caspases activation .

Matching UniProtKB/Swiss-Prot entries

15 entries grouped by strain (browse by keywords)

All proteins are shown (view only 12 complete proteome entries)

6 entries

Berne virus (BEV) reference strain

Select_allDeselect_all
HEMA_BEV Truncated non-functional hemagglutinin-esterase homolog
NCAP_BEV Nucleoprotein (Nucleocapsid protein) (NC) (Protein N)
R1AB_BEV Replicase polyprotein 1ab (pp1ab) (ORF1ab polyprotein) [Cleaved into: Non-structural protein 1 ...
R1A_BEV Replicase polyprotein 1a (pp1a) (ORF1a polyprotein) [Cleaved into: Non-structural protein 1 (nsp1); ...
SPIKE_BEV Spike glycoprotein (S glycoprotein) (E2) (Peplomer protein)
VME1_BEV Membrane protein (M protein) (E1 glycoprotein) (Matrix glycoprotein) (Membrane glycoprotein)

6 entries

Breda virus 1 (BRV-1) reference strain

Select_allDeselect_all
HEMA_BRV1 Hemagglutinin-esterase (HE protein) (EC 3.1.1.53) (E3 glycoprotein)
NCAP_BRV1 Nucleoprotein (Nucleocapsid protein) (NC) (Protein N)
R1A_BRV1 Replicase polyprotein 1a (pp1a) (ORF1a polyprotein) [Cleaved into: Non-structural protein 1 (nsp1); ...
R1AB_BRV1 Replicase polyprotein 1ab (pp1ab) (ORF1ab polyprotein) [Cleaved into: Non-structural protein 1 ...
SPIKE_BRV1 Spike glycoprotein (S glycoprotein) (E2) (Peplomer protein)
VME1_BRV1 Membrane protein (M protein) (E1 glycoprotein) (Matrix glycoprotein) (Membrane glycoprotein)

1 entry

Breda virus 2 (BRV-2)

HEMA_BRV2 Hemagglutinin-esterase (HE protein) (EC 3.1.1.53) (E3 glycoprotein)

1 entry

Human torovirus (HuTV)

HEMA_HUTV Hemagglutinin-esterase (HE protein) (EC 3.1.1.53) (E3 glycoprotein)

1 entry

Porcine torovirus (strain P10) (PoTV)

HEMA_PTV10 Hemagglutinin-esterase (HE protein) (EC 3.1.1.53) (E3 glycoprotein)