Tungrovirus (taxid:187212)

VIRION

Non enveloped, bacilliform particles of 130 x 30 nm. The capsid is presumably based on a T=3 icosahedral symmetry.

GENOME

Circular double stranded DNA of about 8000 base pairs with discontinuities in both strands: one in the transcribed strand and one to three in the non-transcribed strand.

GENE EXPRESSION

ORF2 and ORF3 are expressed by leaky scanning of genomic RNA.

ENZYMES

• Reverse transcriptase
  • RNA-dependent DNA polymerase [RT]
  • DNA-dependent DNA polymerase [RT]
• RNAse H [RT]
• Polyprotein protease (Peptidase A3) [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.