Enveloped, spherical. Diameter from about 42nm. Icosahedric capsid with a T=4 symmetry.
Partially dsDNA circular genome, about 3.2 kb in size. Encodes for 7 proteins. h4. GENE EXPRESSION
- Virus attaches to host receptors through major surface antigen and enters the cell by an unknown mechanism.
- Relaxed circular DNA (RC-DNA) and capsid are transported via microtubules to the nucleus where DNA is released through the nuclear pore, and repaired to form covalently closed circular DNA (cccDNA).
- Transcription by RNA polymerase II of the pregenomic RNA (pgRNA) and subgenomic mRNAs, inducing synthesis of all the viral proteins.
- pgRNA is encapsidated, together with the P protein, and reverse-transcribed inside the nucleocapsid in (-)DNA covalently linked to P protein.
- (+)DNA synthesis from the (-)DNA template generates new RC-DNA.
- Transport to the nucleus of new RC-DNA leads to cccDNA amplification; alternatively, the RC-DNA containing nucleocapsids are enveloped at the ER, and new virions are released by exocytosis.