Deformed Wing Virus
Deformed Wing Virus (DWV) is probably the most commonly encountered virus by beekeepers, particularly since the nearly universal spread of Varroa. It is in the family Iflaviridae.

When varroa are in a brood cell they feed by biting into the pupae. At this time the varroa innoculates the pupa with all the infectious matter it is carrying. for this reason it is important to have an efficient integrated pest management programme (IPM).

It would be easy to confuse slightly affected bees' wings with the rather tattered wings of older foragers. Bees with DWV often have shortened abdomens.

DWV comes in three quasispecies identified to date:
Scientific Beekeeping
The virulent, emerging genotype B of Deformed Wing Virus is closely linked to overwinter honeybee worker loss.
Diversity in a honey bee pathogen: first report of a third master variant of the Deformed Wing Virus quasispecies
Deformed Wing Virus Type A
Kakugo Virus
Deformed Wing Virus Type B was known as
Varroa Destructor Virus 1
Deformed Wing Virus Type C
Type A comes in two variants Kakugo Virus and DWV.

DWV are RNA viruses which mutate a lot in the same way that the bird flu mutates.

DWV type B was originally isolated from varroa mites but has since been reported to replicate in honey bees and cause wing deformities in its host.

It's thought likely that more than one type of DWV will be found in any colony but that one type will dominate. Type A has proven to be more lethal than type B.

Little is known about the symptoms of Type C.

A Comparison of Deformed Wing Virus in Deformed and Asymptomatic Honey Bees