鸭瘟病毒疫苗株与强毒株诱导雏鸭IFN-α mRNA在肝脏中表达的动态定量研究

Dynamics of IFN-α mRNA expression in liver of ducks infected with duck plague virus of different virulence

本研究旨在探讨不同毒力的鸭瘟病毒(DPV)感染对机体IFN-αmRNA表达水平的影响,为DPV的感染与免疫机制提供理论依据。采用Real-time PCR对DPV弱毒株及强毒株接种雏鸭肝脏中的IFN-α mRNA表达水平及病毒荷载量进行动态定量检测,结果显示,弱毒株能引起IFN-αmRNA在肝脏中快速、持续高水平表达;与空白对照相比,在接种后3h上升4倍,9h达到峰值(18.5倍),12h～144h保持在7.8～12.6倍之间,显著抑制了弱毒株的增殖,病毒荷载量较低,表现出感染的自限性;而强毒株只能引起IFN-α mRNA在肝脏中短时间、低水平表达,在感染后72h才达到峰值,为空白对照的4.1倍,持续至132h,以后迅速下降,至144h(濒死时)仅为2.0倍,致使强毒株在肝脏中快速增殖,病毒荷载量与鸭瘟的发病过程密切相关。这些结果提示鸭瘟弱毒株能诱导肝细胞高水平表达IFN-αmRNA,有助于机体建立有效的免疫保护,而强毒株可能通过某种机制抑制IFN-α的表达,利于其建立感染。本研究结果为进一步阐明鸭瘟病毒感染与免疫的分子机制提供了有价值的实验数据。

To understand the mechanisms of DPV infection and immunity, the IFN-α mRNA expression in liver was investigated after infection with virulent and attenuated duck plague virus. Ducks were inoculated with either virulent or attenuated DPV, and virus load and IFN- α mRNA levels were monitored by real-time PCR method. High level and persistent IFN- α mRNA expression in liver （7.8 to 18 folds increase） could be induced by attenuated DPV. The attenuated DPV replicated in liver with a relative low copy number. In comparison, the virulent DPV induced a short time and low level IFN-α mRNA expression with up to 4.1-fold increase but decreased gradually. At the same time, the virus load increased dramatically. These results indicated that high level expression of IFN-α in liver induced by attenuated DPV could enhance immunity against DPV infection, while virulent DPV would establish infection by, at least partly, blocking the IFN- α expression.