Satellite virus: Replicated and packaged by helper Begomoviruses or Mastrevirus
GENOME
Circular, single-stranded DNA genome of 700 to 1,350 nucleotides that have no sequence identity to their helper begomoviruses. Contains an adenine rich region, and a satellite conserved region (SCR).
GENE EXPRESSION
The genome encodes either none or one protein.
REPLICATION
NUCLEAR
- Virus penetrates into the host cell.
- Uncoating, the viral ssDNA genome penetrates into the nucleus.
- The ssDNA is converted into dsDNA with the participation of cellular factors.
- bidirectional dsDNA transcription from the IR promoter produces viral mRNAs and translation of viral proteins.
- Replication is initiated by cleavage of the(+)strand by REP, and occurs by rolling circle producing ssDNA genomes.
- These newly synthesized ssDNA can either
a) be converted to dsDNA and serve as a template for transcription/replication
b) be encapsidated by CP and form virions released from the cell by budding
c) be transported outside the nucleus, to a neighboring cell through plasmodesmata (cell-cell movement) with the help of viral movement proteins.