Notes on Genus: Iteravirus
Type member: Bombyx mori densovirus 1
This is one of the genera in the subfamily Densovirinae
, the insect pathogens in the family Parvoviridae
. Members are distinguished from those of the other genera by genome size (about 5 kb), genomic organisation and phylogenetic analysis. The name, from the latin itero
="to repeat" is taken from the inverted terminal repeat in the DNA.
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 kb long with an inverted terminal repeat of 225nts but which does not form a stem loop. Equal numbers of plus and minus strands are encapsidated.
Genus Genomic Organization
The 5' half of the genome has two nested ORFs in different reading frames that encode the non-structural proteins. A single structural ORF in the 3'-half of the genome is translated by a leaky scanning strategy to produce virion proteins of different sizes.
Type Member Genomic Organization
There are 3 major ORFs in the same orientation:
- Non-structural protein NS1, 89.3 kDa
- Non-structural protein NS2, 51.9 kDa
- Capsid protein VP, 74.9 kDa but translated by leaky scanning to produce products of differing length (with the same C-terminus)