Abstract
Since 2017, duck spleen necrosis caused by a new variant duck
orthoreovirus (N-DRV) infection had been observed in many provinces in
China. This disease causes the growth and development of ducks to be
retarded, and the feed return rate is reduced. Because the target organ
of the disease is mainly the spleen, the immune suppression of the
diseased ducks is easy to secondary infection of other pathogens. In
this study, we successfully constructed a breeding duck artificial
infection model and found that N-DRV infection can cause pathological
changes such as ovarian hemorrhage, follicle atrophy, and fallopian tube
bleeding in breeding ducks, resulting in a significant reduction in the
fertilization rate and hatching rate of breeding eggs. The qPCR method
was used to detect viral RNA in samples of egg vitelline membrane, duck
embryo, and duckling’s spleen. It was found that viral RNA was present
in the above samples. Although there were no obvious clinical symptoms
in the early stage of ducklings, autopsy revealed obvious pathological
changes in the spleen and other organs. The sequence distance and
phylogenetic analysis of the strain re-isolated from the spleen samples
of ducklings (named N-DRV-SD19) confirmed that N-DRV-SD19 was consistent
with the strain N-DRV-XT18 used for the infection of the breeding ducks.
The findings of the above research confirmed that N-DRV can be
vertically transmitted through eggs, which will provide an important
reference for the prevention and control of the disease.