Animal experiments
Ninety 3-day-old EDSV sero-negative Pekin ducklings,
which were bacterial and virus pathogen-free, were used
for the experimental infection. The ducklings were
classified into three groups. Each group consisted of 20
ducklings for pathogenicity analysis and 10 ducklings for
survival analysis. The two groups were infected intratracheally
by inoculation with 1010 TCID50/0.02 ml of the
D11-JW-012 and D11-JW-017 field isolates, respectively.
The control group was inoculated with PBS. Five ducklings
were euthanized at days 4, 6, 12, and 16 days postinfection
(dpi) and subjected to gross and histological
analyses, viral detection by PCR, and ciliary activity assay
in the trachea. All remaining infected and control ducks
were processed in the same manner at 29 dpi. The
ducklings were wing-banded individually and reared
under uniform management care in an isolator. All
experimental procedures and animal management procedures
were undertaken in accordance with the requirements
of the Animal Care and Ethics Committees of
Chonbuk National University. The animal facility of the
Chonbuk National University is fully accredited by the
National Association of Laboratory Animal Care.