VIRION
Non enveloped, large (45-50 nm diameter) icosahedral particles composed of 420 subunits with a T=7 symmetry. It has not been described whether handedness of capsid is laevo or dextro, here the pictures dsplays a laevo form.
GENOME
Monopartite, open circular, double stranded DNA of about 7200 base pairs with discontinuities in both strands: one in the transcribed strand and one to three in the non-transcribed strand.
GENE EXPRESSION
ORF1 polyprotein is presumably cleaved into several chains by viral protease.
ENZYMES
- Reverse transcriptase
- RNAse H [RT]
- Polyprotein protease (Peptidase A?) [PRO]
REPLICATION
CYTOPLASMIC / NUCLEAR
- Attachment of viral proteins to host receptors mediates entry into the host cell.
- The viral dsDNA is released into the nucleus.
- Transcribed by host RNA polymerase II.
- mRNA translation produces viral proteins.
- Genomic RNA is retrotranscribed into new dsDNA genomes in the cytoplasm.
- Genomes are encapsidated by the capsid protein and form new virions.
- The virion infects either a new cell by plasmodesmata movement, or by insect vector uptake.