Hi Bill,
If it seems as if there is no one right answer to this question, that's
because there isn't. I can't find any discussion of the effect the virus has
on the mites themselves, though it is apparent that viruses multiply in the
mites' bodies. 

The relationship among honeybees, DWV, and Varroa
jacobsoni is obviously complex but it is possible to
postulate a progression of events on the arrival of the
mites in a colony. Having infested a colony, V. jacobsoni
will either acquire DWV from naturally infected (but
asymptomatic) bees or bring it with them from their
previous colony. The viruses may then replicate within
the mites and, ultimately, high virus levels of DWV will
be transmitted to the brood.

Where two or more mother mites
enter a cell, only one needs to be carrying virus to
cross-infect the other(s) and the offspring by infecting
the common food source, i.e., the developing bee.

The Transmission of Deformed Wing Virus between Honeybees
Journal of Invertebrate Pathology 73, 101–106 (1999)

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