VIRION
Non-enveloped, round, T=1 icosahedral symmetry, about 20 nm in diameter.
GENOME
Multi-part ssDNA genome (+), consisting of 3 circular segments of about 1kb in size. Each ssDNA segment has a common stem-loop region and is encapsidated in a separate particle. In addition to the genomic DNA, up to 9 "Alphasatellites:/by_protein/8576 can be found. One of these "Alphasatellites:/by_protein/8576 is common to all virus isolates, suggesting that the Rep protein it encodes may serve to initiate replication of these DNAs.
GENE EXPRESSION
Each ssDNA genome segment is monocistronic.
ENZYMES
- Cress-type Endonuclease [brought by "Alphasatellites:/by_protein/8576 DNA]
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 that will be released in the extracellular space. c) be transported outside the nucleus, to a neighboring cell through plasmodesmata (cell-cell movement) with the help of viral movement proteins.