Abstract: Duck tembusu virus (DTMUV) infection is a disease that causes a decline in laying ducks and brings great economic losses to the poultry breeding industry. In this study, the virus location and pathological damage of DTMUV-infected duck ovaries were observed to understand the effect of DTMUV on ovarian damage. Pathological necropsy, routine paraffin sections, HE staining, and immunohistochemistry were used to study diseased ducks naturally infected with DTMUV. The clinical manifestations of laying ducks were mainly characterized by a sudden drop in egg production. In severe cases, they could not stand steady, fell to the ground and convulsed, and finally died of exhaustion. Necropsy showed that follicles were hemorrhage and rupture. Histopathological changes were mainly the proliferation, apoptosis or necrosis of granulosa cells in growing follicles and mature follicles; there were a large number of vacuolar cells and small arteries around the follicles. Arterial smooth muscle cell necrosis and a large number of inflammatory cells infiltrated; immunohistochemical examination results showed that the proliferating vacuolar cells are epithelial cells, and DTMUV is mainly located in the granular cells of the follicles. According to the observation results, DTMUV is mainly distributed in the granulosa cells. The granulosa cells proliferate, apoptosis or necrosis, which leads to follicle atresia, and causes the egg production of laying ducks to decrease. It provided a theoretical basis for elucidating the pathogenic mechanism of DTMUV infection.

Key words: duck tembusu virus(DTMUV), natural infection, egg production, pathological damage, ovary