Notes on Genus: Isavirus
enveloped spheres or pleomorphic
Type member: Infectious salmon anemia virus
The genus Isavirus B
is a member of the family Orthomyxoviridae
. It is named from the type (and only) member I
nemia virus, which infects fish.
Virions spherical or pleomorphic, enveloped, 80-120 nm in diameter, with projections 4-6 nm in diameter and 10-14 nm long.
Single-stranded negative sense RNA in 8 segments totalling about 14.5 kb. The segments do not have a genome-linked protein (VPg) at their 5'-terminus nor a 3'-polyA tail.
Genus Genomic Organization
There are 8 RNA segments. The larger genome segments each encode a single protein while the two smallest segments each encode two proteins.
Type Member Genomic Organization
There are 8 RNA segments:
- RNA1 (2.3 kb) encodes a basic polymerase (PB2) of 80 kDa
- RNA2 (2.2 kb) encodes a basic polymerase (PB1) of 80 kDa
- RNA3 (2.1 kb) encodes the coat protein (Nucleoprotein, NP) of 68 kDa
- RNA4 (1.8 kb) encodes an acid polymerase (PA) of 65 kDa
- RNA5 (1.5 kb) encodes an acetylesterase of 49 kDa
- RNA6 (1.3 kb) encodes a hemagglutinin (HA) of 43 kDa
- RNA7 (1.1 kb) encodes two matrix proteins (M1 and M2) of 34 and 17 kDa
- RNA8 (0.9 kb) encodes two non-structural proteins (NS1 and NS2) of 27 and 22 kDa