Mamastrovirus

VIRION

Non-enveloped, spherical, capsid of about 35 nm with T=3 icosahedral symmetry. Surface projections are small and surface appears rough, spikes protruding from the 30 vertices.
VP90 capsid precursor protein undergoes C-terminal cleavages by host caspases to generate VP70 during virus maturation (180 copies of VP70 per particle). Infectious particles are generated by further cleavages of VP70 by extracellular proteases resulting in three structural proteins, VP34, VP27 and VP25 .

GENOME

Monopartite, linear ssRNA(+) genome of 6.8-7kb in size. The 5'-terminus is linked to a VPg protein and the 3'-terminus has a poly(A) tract.

GENE EXPRESSION

The virion RNA is infectious and serves as both the genome and viral messenger RNA. The genome contains three overlapping open reading frames (ORF1a, ORF1b, and ORF2). The nonstructural proteins are translated from the genomic RNA as two large polyproteins, nsP1a and nsP1a/1b, through a translational ribosomal frameshifting mechanism. ORF1a and ORF1b encode the viral protease and polymerase respectively (and probably other proteins involved in genome replication). ORF2 is expressed from a subgenomic RNA and encodes the VP90 capsid precursor protein.

REPLICATION

CYTOPLASMIC

  1. Attachement to host receptors probably mediates endocytosis of the virus into the host cell.
  2. Uncoating, and release of the viral genomic RNA into the cytoplasm.
  3. Viral RNA is translated into two processed polyproteins to produce replication proteins.
  4. Replication occurs in viral factories made of membrane vesicles derived from the ER. A dsRNA genome is synthesized from the genomic ssRNA(+).
  5. The dsRNA genome is transcribed/replicated thereby providing viral mRNAs/new ssRNA(+) genomes.
  6. Subgenomic RNA translation gives rise to the capsid protein precursor.
  7. Assembly of new virus particles.
  8. Non-lytic virus release and maturation of the capsid by proteolytic cleavages.

Host-virus interaction

Adaptive immune response inhibition

Human astrovirus inhibits host complement factors .

Apoptosis modulation

Host cell apoptosis and host caspases activation seems necessary for maturation of human astrovirus particles .

Matching UniProtKB/Swiss-Prot entries

23 entries grouped by protein (browse by keywords)

All proteins are shown (view only 18 complete proteome entries)

11 entries

Capsid polyprotein VP90

Select_allDeselect_all
CAPSD_HASV1
Human astrovirus-1 (HAstV-1) reference strain
CAPSD_HASV2
Human astrovirus-2 (HAstV-2)
CAPSD_HASV3
Human astrovirus-3 (HAstV-3)
CAPSD_HASV4
Human astrovirus-4 (HAstV-4)
CAPSD_HASV5
Human astrovirus-5 (HAstV-5)
CAPSD_HASV6
Human astrovirus-6 (HAstV-6)
CAPSD_HASV7
Human astrovirus-7 (HAstV-7)
CAPSD_HASV8
Human astrovirus-8 (HAstV-8)
CAPSD_MASV1
Mink astrovirus 1 (MAstV-1)
CAPSD_OASV1
Ovine astrovirus 1 (OAstV-1)
CAPSD_PASV1
Porcine astrovirus 1 (PAstV-1)

6 entries

Non-structural polyprotein 1A

Select_allDeselect_all
NS1A_HASV1
Human astrovirus-1 (HAstV-1) reference strain
NS1A_HASV4
Human astrovirus-4 (HAstV-4)
NS1A_HASV5
Human astrovirus-5 (HAstV-5)
NS1A_HASV8
Human astrovirus-8 (HAstV-8)
NS1A_MASV1
Mink astrovirus 1 (MAstV-1)
NS1A_OASV1
Ovine astrovirus 1 (OAstV-1)

6 entries

Non-structural polyprotein 1AB

Select_allDeselect_all
NS1AB_HASV1
Human astrovirus-1 (HAstV-1) reference strain
NS1AB_HASV4
Human astrovirus-4 (HAstV-4)
NS1AB_HASV5
Human astrovirus-5 (HAstV-5)
NS1AB_HASV8
Human astrovirus-8 (HAstV-8)
NS1AB_MASV1
Mink astrovirus 1 (MAstV-1)
NS1AB_OASV1
Ovine astrovirus 1 (OAstV-1)