鸭肿头出血症病毒强毒的致病性及感染组织细胞的超微病理变化

Pathogenicity of duck swollen head haemorrhagic disease virus and ultrastructural pathological changes in experimentally-infected ducks

将鸭肿头出血症病毒（DSHDV）强毒株以不同途径接种10日龄鸭胚，研究了病毒在鸭胚中的繁殖规律，并用透射电镜观察了感染鸭胚各组织器官的超微结构变化，同时用DSHDV人工感染不同日龄雏鸭，比较了不同感染途径对雏鸭的致病性和对不同日龄雏鸭的致病性。结果显示，尿囊腔和卵黄囊2种途径均能使病毒在鸭胚上繁殖并传代，对鸭胚的半数致死量分别为10^-7.24／0．2mL和10^-6.4／0．2mL。病毒感染鸭胚后，电镜下可观察到肝和尿囊膜中的病毒粒子，病毒粒子呈球形或椭圆形，大小为60～80nm，无囊膜；病毒在细胞浆内复制，可形成特征性包涵体；病毒侵害的主要靶器官为尿囊膜与肝，细胞器的变化主要表现为粗面内质网扩张以及线粒体肿胀和嵴断裂、消失。病毒经肌肉注射、口服和滴鼻均能使28日龄鸭感染发病，致死率分别为86％、89％和97％。研究表明，DSHDV能很好地在鸭胚上生长并致鸭胚各组织器官超微结构发生变化，不同感染途径均能使雏鸭感染发病且致病性强。

To study the reproduction laws of duck swollen head haemorrhagic disease virus（DSHDV）, 10-day-old duck embryo was inoculated with DSHDV velogenic strain at different routes. The ultrastructures of the duck embryo tissues were observed by transmission electron microscope（TEM）. Ducklings at different age were experimentally challenged with DSHDV to compare the pathogenicity at different routes of infection. The results showed that the DSHDV was able to reproduce and passage through the duck embryo by the routes of allantoic cavity and vitelline sac infection. The LD50 were 10^-7.24/0. 2 mL and 10^-6.4/0.2 mL,respectively. The virions were observed in the liver and chorioallantoic membrane of infected duck embryo by TEM. The virus was globular,oval and nonenveloped and ranged from 60-80 nm in diameter. The virus replicated in the intracytoplasm and formed inclusion bodies. The target organ where virus located were ehorioallantoic membrane and liver. The organelle changes included dilation of rough endoplasmic reticulum, mitochondria swelling and crista fragmentation. The lethality rate of the 28-day-old ducks challenged with DSHDV at intramuscular injection, oral administration and intranasal routes were 86 %, 89 % and 97 %, respectively. The results demonstrated that DSHDV can grow in the duck embryo and lead to ultramicrostructure changes in some organs. The DSHDV caused a disease in ducklings challenged with DSHDV at different routes.