Notes on Genus: Erythrovirus
Type member: B19 virus
This is one of the genera in the subfamily Parvovirinae
, the vertebrate pathogens in the family Parvoviridae
. Members are distinguished from those of the other genera by the presence of inverted repeats but not hairpin structures at both ends of the genome, and a single mRNA promoter. There is efficient replication in erythrocyte precursors, hence the name.
Virions isometric (icosahedral), not enveloped, 18-26 nm in diameter, made of 60 units of the capsid protein.
Linear, single-stranded monopartite DNA, about 5.0-5.6 kb long with inverted repeats at both ends of the genome and one mRNA promoter. Positive and negative strand DNA occur in the virions in approximately equal proportions.
Genus Genomic Organization
As in other members of the subfamily, there are two major ORFs on the same strand. These encode the non-structural (replication) protein and the capsid protein. mRNA splicing may result in products that differ from those of simple computer predictions but which have not always been experimentally determined. The capsid protein may also undergo proteolytic cleavage.
Type Member Genomic Organization
There are 2 major ORFs in the same orientation and three major protein products:
- Non-structural protein NS1, 74.0 kDa
- Capsid protein VP1 (86.0 kDa)
- Capsid protein VP2 (60.8 kDa) with the same C-terminus as VP1