We have had an interesting problem with our experimental animals, the
white Pekin duck (Anas platyrhynchos). Over the past 6 months we have
seen a drastic decrease in the number of ducklings which have hatching
from eggs produced from our flocks of uninfected and duck hepatitis B
virus-infected animals; the hatch rate has gone from 40-50% to =BE5%. Th=
problem is not in the fertilization process since the numbers represent
eggs which show proper development of the duck embryo upon candling 1 wee=
prior to expected hatch date. The problem is not with the presence of th=
DHBV virus since failure to hatch is seen with eggs from uninfected
animals (as well, DHBV establishes chronicity in this animal model and
does not produce an overt pathology).
So...what could it be? Too much interbreeding of the laying stock? Hard t=
fathom since we retire/replenish breeding stock every 6-8 months. This
also does not explain why embryo development appears to be fine yet these
ducks fail to hatch.
One thought that came to me is the possibility of a viral infection which
might be associated with embryo mortality. After checking MedLine, a
candidate virus appeared - the duck plague virus (an avian herpesvirus).
Anyone wish to comment on whether the symptomology is consistent with DPV
Of all the "hits" with DPV, there does not appear to be a PCR-based or
hybridization-based detection system; all detection methods I've found ar=
based on electron microscopy or are tissue culture based. Alternative
methods of detection?=20
Bottom line is 1) can anyone suggest an alternative etiology for the
decreased hatch rate, 2) are there any publications which might be a
suitable read for viral zoonoses (particularly avian) and 3) why am I
rambling on so long ;-).
Thanks in advance...I'm off to check GenBank for avian viral sequences.
Karl the hepB guy
tyr-2 at bones.biochem.ualberta.ca