Petuvirus (taxid:186845)

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
  • RNA-dependent DNA polymerase [RT]
  • DNA-dependent DNA polymerase [RT]
• RNAse H [RT]
• Polyprotein protease (Peptidase A?) [PRO]

REPLICATION

CYTOPLASMIC / NUCLEAR

1. Attachment of viral proteins to host receptors mediates entry into the host cell.
2. The viral dsDNA is released into the nucleus.
3. Transcribed by host RNA polymerase II.
4. mRNA translation produces viral proteins.
5. Genomic RNA is retrotranscribed into new dsDNA genomes in the cytoplasm.
6. Genomes are encapsidated by the capsid protein and form new virions.
7. The virion infects either a new cell by plasmodesmata movement, or by insect vector uptake.