Deformed wing virus
| Deformed wing virus | |
|---|---|
 |
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| Carniolan honey bee with DWV | |
| Virus classification | |
| Group: | Group IV ((+)ssRNA) |
| Order: | Picornavirales |
| Family: | Iflaviridae |
| Genus: | Iflavirus |
| Species: | Deformed wing virus |
Deformed wing virus (DWV) is an RNA virus, one of 22 known viruses affecting honey bees. While most commonly infecting the honey bee, Apis mellifera, it has also been documented in other bee species, like Bombus terrestris, thus, indicating it may have a wider host specificity than previously anticipated. The virus was first isolated from a sample of symptomatic honeybees from Japan in the early 1980s and is currently distributed worldwide. Found also in pollen baskets and commercially reared bumblebees (Graystock et al 2013). Its main vector in A. mellifera is the Varroa mite. It is named after what is usually the most obvious deformity it induces in the development of a honeybee pupa, which is shrunken and deformed wings, but other developmental deformities are often present.
The viral genome was published in 2006. The genome is 10140 nucleotides in length excluding the poly(A) tail and contains a single large open reading frame encoding a 328-kilo Dalton (kDA) polyprotein. 5' of the central coding sequence is a 1144-nucleotide nontranslated leader sequence (UTR). 3' coding sequence is a 317-nucleotide nontranslated region which is followed by a poly(A) tail.
The genome is 29.5% adenosine, 15.8% cytosine, 22.4% guanine and 32.3% uracil. Analysis of codon use found 39.5% uracil and 26.8% adenosine in the third base position.There are three major structural proteins - VP1 (44 kDa), VP2 (32 kDa), and VP3 (28 kDa). These lie in the N-terminal section of the polyprotein. The C-terminal part of the polyprotein contains sequence motifs typical of well-characterized picornavirus nonstructural proteins: an RNA helicase, a chymotrypsin-like 3C protease and an RNA-dependent RNA polymerase.
VP1 is encoded between codons 486 to 880 and VP3 lies between codons 913 and 1063. The boundaries of VP2 are not as well defined but it is encoded 5' of VP1. There may be a small protein (VP4) encoded between codons 464 and 486 but this protein has not been confirmed to be present in the genome.
Lying 5' to VP2 is a very variable leader peptide (L protein). Despite occupying 7.3% of the polyprotein it is responsible for 26.2% to 33.3% of the variation found between the Iflaviridae. It may be involved in the inhibition of host cap-dependent mRNA translation and stimulation of viral internal ribosome entry site activity.
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