Notes on Genus: Circovirus
Type member: Porcine circovirus-1
The genus Circovirus
(from the cir
nformation of the DNA) is one of two genera in the family Circoviridae
and contains viruses with genomes smaller than 2.2kb that are translated from ORFs in both directions.
Virions isometric (icosahedral), not enveloped, 12-21 nm in diameter.
Monopartite circular single-stranded DNA of 1.7-2.2 kb. The origin of replication contains a nonanucleotide sequence TAGTATTAC at the apex of a stem loop.
Genus Genomic Organization
There are two well-characterised ORFs in all the sequenced viruses. A replication protein (V1) of 33-36 kDa is encoded in the virion (positive sense) and a coat protein (C1) of 19-32 kDa in the negative sense. In most members, one or more additional hypothetical ORFs have been identified.
Type Member Genomic Organization
The two well-characterised ORFs are:
- V1 (+ sense): 35.6 kDa, Replication protein
- C1 (- sense): 23.7 kDa, Coat protein