Herpes-like
virus infections in hatchery-reared bivalve larvae in Europe: specific viral
DNA detection by PCR
T.
Abstract:
Periodic losses in oyster hatcheries are regularly
reported in Europe. Herpes-like virus infections seem to play a key role.
Polymerase chain reaction (PCR) was used to investigate the presence of
herpes-like virus DNA in larval samples belonging to different bivalve
species from different geographical origins. Seventeen samples of the 81
analysed appeared positive for the herpes-like virus DNA by PCR. These
results confirm previous data indicating that herpes-like virus infections
occur in commercial French hatcheries. Polymerase chain reaction positive
results were also obtained for bivalve larval samples originating from Spain
and the UK. The number of virus DNA positive samples depended on the primer
pair used. The primer pair C2/C6 appears well adapted for herpes-like virus
DNA detection because of processing ease and great sensitivity. Positive
samples were observed in four bivalve species: Crassostrea gigas, Ostrea
edulis, Ruditapes decussatus and Ruditapes philippinarum.
Herpes-like virus DNA detection is reported in larval R. decussatus
for the first time. Many samples in which viral DNA was detected by PCR
correspond to larval batches presenting mortalities. Herpes-like viruses may
be one of the causative agents of mortalities observed in bivalve
hatcheries.
(IFREMER,
Laboratoire de Génétique et Pathologie, B. P. 133,17390 La Tremblade,
France, e-mail: trenault@ifremer.fr)