Brevihamaparvovirus (taxid:2733230)

VIRION

Non-enveloped, round, T=1 icosahedral symmetry, 21-22 nm in diameter. The capsid consists of 60 copies of CP protein.

GENOME

Linear, ssDNA genome of about 4kb in size, with long inverted terminal repeats. Both positive and negative strands are encapsidated, but a majority of strands are of negative polarity (85%).
The genome is replicated through rolling-hairpin mechanism.

GENE EXPRESSION

Host proteins transcribe the genomes into mRNAs.

ENZYMES

• Parvo-type Endonuclease [NS1]

REPLICATION

NUCLEAR

1. Attachement to host receptors initiates clathrin-mediated endocytosis of the virion into the host cell.
2. The virion penetrates into the cytoplasm via permeabilization of host endosomal membrane.
3. Microtubular transport of the virion toward the nucleus.
4. The viral ssDNA genome penetrates into the nucleus.
5. The ssDNA is converted into dsDNA by cellular proteins.
6. dsDNA transcription gives rise to viral mRNAs when host cell enters S phase and translated to produce viral proteins.
7. Replication occurs through rolling-hairpin mechanism, with NS1 endonuclease binding covalently to the 5' genomic end.
8. Individual ssDNA genomes are excised from replication concatemers by a process called junction resolution.
9. These newly synthesized ssDNA can either
   a) be converted to dsDNA and serve as a template for transcription/replication
   b) be encapsidated to form new virions that are released by cell lysis.

Host-virus interaction

Apoptosis modulation

IHHNV induces apoptosis and caspases activation in p53-deficient cells .