Non enveloped, icosahedral virion with a double capsid structure, about 80 nm in diameter. Pentameric turrets sit on the outside of the innermost capsid. The outer capsid has a T=13 icosahedral symmetry, the inner capsid a T=2 icosahedral symmetry.
Virion maturation schemes


Segmented dsRNA linear genome. Contains 10 segments: L1, L2, L3, M1, M2, M3, S1, S2, S3, S4, coding for 12-13 proteins. Segments size range from 1,189 to 3,916nt (MRV-3De). Genome total size is 23.5 Kb (MRV-3De). MuNSC and S.1s are produced by leaky scanning of mRNA M3 and S1 respectively.


The dsRNA genome is never completely uncoated, to prevent activation of antiviral state by the cell in response to dsRNA. The viral polymerase lambda3 synthesizes a capped and non-polyadenylated monocistronic mRNA from each dsRNA segment. These capped mRNAs are translocated to the cell cytoplasm where they are translated.



  1. Attachement to host receptors mediates clathrin-mediated endocytosis of virus into host cell.
  2. Particles are partially uncoated in endolysosomes, but not entirely, and penetrate in the cytoplasm.
  3. Early transcription of the dsRNA genome by viral polymerase occurs inside this sub-viral particle (naked core), so that dsRNA is never exposed to the cytoplasm.
  4. Full-length plus-strand transcripts from each of the dsRNA segments are synthesized. These plus-strand transcripts are used as templates for translation.
  5. Viral proteins and genomic RNAs aggregates in cytoplasmic viral factories.
  6. (+)RNAs are encapsidated in a sub-viral particle, in which they are transcribed to give RNA (-) molecules with which they become base-paired to produce dsRNA genomes.
  7. The capsid is assembled on the sub-viral particle.
  8. Mature virions are released presumably following cell death and associated breakdown of host plasma membrane.

Host-virus interaction

Apoptosis modulation

Mammalian reovirus mediates host cell apoptosis through the activation of death receptors, including TRAIL, TNFR and Fas . Activation of these death receptors induces the activation downstream caspases (caspase-3).

Avian orthoreovirus induces host cell apoptosis probably through upregulation of p53 (activation of DNA-damage signalling) by viral sigmaC protein .

Autophagy modulation

Avian orthoreovirus also seems to induces autophagy .

Innate immune response inhibition

Mammalian orthoreoreovirus σ3 protein binds to dsRNA and inhibits the PRK-mediated antiviral response of the host cell .
Mammalian orthoreovirus &mu2; protein from strain Lang (T1L) inhibits IFN-beta-induced reporter gene expression .

Avian orthoreovirus σA protein binds to dsRNA and inhibits the PRK-mediated antiviral response of the host cell .

Cell-cycle modulation

Human and avian reovirus induce G2/M cell cycle arrest .

Matching UniProtKB/Swiss-Prot entries

34 entries grouped by strain (browse by keywords)

All proteins are shown (view only 32 complete proteome entries)

11 entries

Reovirus type 1 (strain Lang) (T1L) (Mammalian orthoreovirus 1) reference strain

Select_all Deselect_all  
LMBD1_REOVLInner capsid protein lambda-1 (Lambda1) (EC (ATP-dependent DNA ...
LMBD2_REOVLOuter capsid protein lambda-2 (Lambda2) (Lambda2(Cap))
MU1_REOVLOuter capsid protein mu-1 (Mu1)
MU2_REOVLMicrotubule-associated protein mu-2 (Mu2)
MUNS_REOVLProtein mu-NS (MuNS)
RDRP_REOVLRNA-directed RNA polymerase lambda-3 (Lambda3) (EC (Lambda3(Pol))
SIG1S_REOVLProtein sigma-1-small (Sigma1s) (Sigma-s) (Sigma1NS) (Sigma1bNS) (p14)
SIGM1_REOVLOuter capsid protein sigma-1 (Sigma1) (Cell attachment protein) (Hemagglutinin)
SIGM2_REOVLInner capsid protein sigma-2 (Sigma2)
SIGM3_REOVLOuter capsid protein sigma-3 (Sigma3)
SIGNS_REOVLProtein sigma-NS (SigmaNS)

11 entries

Reovirus type 2 (strain D5/Jones) (T2J) (Mammalian orthoreovirus 2)

Select_all Deselect_all  
LMBD1_REOVJInner capsid protein lambda-1 (Lambda1) (EC (ATP-dependent DNA ...
LMBD2_REOVJOuter capsid protein lambda-2 (Lambda2) (Lambda2(Cap))
MU1_REOVJOuter capsid protein mu-1 (Mu1)
MU2_REOVJMicrotubule-associated protein mu-2 (Mu2)
MUNS_REOVJProtein mu-NS (MuNS)
RDRP_REOVJRNA-directed RNA polymerase lambda-3 (Lambda3) (EC (Lambda3(Pol))
SIG1S_REOVJProtein sigma-1-small (Sigma1s) (Sigma-s) (Sigma1NS) (Sigma1bNS) (p14)
SIGM1_REOVJOuter capsid protein sigma-1 (Sigma1) (Cell attachment protein) (Hemagglutinin)
SIGM2_REOVJInner capsid protein sigma-2 (Sigma2)
SIGM3_REOVJOuter capsid protein sigma-3 (Sigma3)
SIGNS_REOVJProtein sigma-NS (SigmaNS)

11 entries

Reovirus type 3 (strain Dearing) (T3D) (Mammalian orthoreovirus 3)

Select_all Deselect_all  
LMBD1_REOVDInner capsid protein lambda-1 (Lambda1) (EC (ATP-dependent DNA ...
LMBD2_REOVDOuter capsid protein lambda-2 (Lambda2) (Lambda2(Cap))
MU1_REOVDOuter capsid protein mu-1 (Mu1)
MU2_REOVDMicrotubule-associated protein mu-2 (Mu2)
MUNS_REOVDProtein mu-NS (MuNS)
RDRP_REOVDRNA-directed RNA polymerase lambda-3 (Lambda3) (EC (Lambda3(Pol))
SIG1S_REOVDProtein sigma-1-small (Sigma1s) (Sigma-s) (Sigma1NS) (Sigma1bNS) (p14)
SIGM1_REOVDOuter capsid protein sigma-1 (Sigma1) (Cell attachment protein) (Hemagglutinin)
SIGM2_REOVDInner capsid protein sigma-2 (Sigma2)
SIGM3_REOVDOuter capsid protein sigma-3 (Sigma3)
SIGNS_REOVDProtein sigma-NS (SigmaNS)

1 entry

Avian reovirus (strain S1133) (ARV)

SIGC_ARVS1Sigma-C capsid protein (Sigma-3 protein)