Juanse, I found Nazzi's paper to be of great interest, since it proposes a
plausible mechanism for the problems that we've been seeing with bees since
shortly after the arrival of varroa:

"This suggests that any bee antiviral immune response relying on
this transcription factor is reduced, but not strongly suppressed, as
happens in more aggressive viral pathogens, which are able to
interfere with NF-kB, either directly or indirectly, by targeting
upstream events that control NF-kB activation. Therefore,
the delicate balance of covert DWV infections could be
disrupted by any stress factor that activates a response triggered by
NF-kB. In other words, the limited availability of this transcription
factor seems to be sufficient to maintain under control the DWV
infection, which, however, may undergo intense replication if NFkB
is substantially subtracted by any other pathway activated by
acute responses to stress factors."

In other words, since nearly 100% of individual bees are keeping a DWV
infection in check, it makes the entire colony more susceptible to any sort
of additional stress or pathogen.  And when things turn such that the check
on DWV is removed, then it can explode.  I see a similar phenomenon when
inoculating with IAPV.
-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

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