VIRION
Non-enveloped, round, T=1 icosahedral symmetry, about 20 nm in diameter.
GENOME
Monopartite, circular, ssDNA genome genome of about 2.17 kb. There are coding regions in both the virion (positive) and complementary (negative) sense strands.
The replication (Rep) protein initiates and terminates rolling circle replication. Two intergenic regions separate the two ORFs, the large intergenic region (LIR, 133 nt)
and the small intergenic region (SIR, 119 nt). There is a potential stem-loop structure in the LIR that includes a nona-nucleotide sequence (TAATATTAT) where ssDNA replication is initiated.
The short intergenic region contains bidirectional polyadenylation signals.
GENE EXPRESSION
Transcription is bidirectional from the long intergenic region (LIR) which contains two divergent promoters. The resulting transcripts encode a capsid protein and a replication-associated protein.
ENZYMES
REPLICATION
- Virus attaches to host cell, and genomic DNA penetrates into the cytoplasm.
- Presumably the ssDNA is converted to dsDNA.
- Transcription of viral genes, possibly by a host RNA polymerase.
- Genome replication, possibly by rolling circle
- Assembly and release of virions.