中文摘要：

【目的】比较和评价了敲除meq基因的MDV感染性克隆作为新型DNA疫苗的免疫保护效果。【方法】将1日龄SPF鸡饲养于正压过滤空气的SPF动物饲养隔离罩内。1日龄时,将SPF鸡以10μg/只的剂量通过大腿肌肉注射的方式接种溶解于PBS缓冲液中的敲除meq基因的MDV感染性克隆GX0101 Δmeq-BAC,分别在免疫后5天或12天以500PFU/只的剂量接种超强毒rMd5。饲养90天,观察死亡情况,对每一只鸡剖检并取心脏与肝脏做石蜡切片,进行病理观察。【结果】免疫5天后攻毒,CVI988/Rispens对超强毒rMd5的保护指数可达到87%,GX0101 Δmeq-BAC对rMd5的保护指数仅达33%;而免疫12天后对rMd5的保护指数为53%。【结论】相对于细胞结合疫苗CVI988/Rispens,DNA疫苗在机体内的病毒拯救是使其获得保护力的前提条件,因此有一定的免疫空当期。以GX0101 Δmeq-BAC作为疫苗免疫不仅能使雏鸡在受到超强毒感染时发病延迟,而且还能提供较好的免疫保护效果。

英文摘要：

[Objective]To evaluate the immuno-protective effect of GX0101 Δmeq-BAC containing an infectious meq-null Marek＇s disease virus genome.[Method]One-day-old SPF birds were reared separately in isolators with positive filtered air.On day 1 of age,chickens immunized with 10μg of GX0101 Δmeq-BAC suspended in PBS,challenge infection with 500PFU very virulent rMD5 was performed at day 5 and 12 post-immunization separately.During 90 days after challenge,all bird were recorded and checked for necropsy.The samples of heart and liver were collected for histo-sections.[Results]The protective index of the two vaccines used was 87 and 33 for CVI988 /Rispens and GX0101 Δmeq-BAC,respectively,after challenged with the very virulent virus rMd5 at day 5 post-immunization.When challenged with rMd5 at day 12 post-immunization,the protection index of GX0101 Δmeq-BAC increased to 53%.[Conclusion]Except that GX0101 Δmeq-BAC can confer protection against very virulent Marek＇s disease virus,a delay in the development of Marek＇s disease could be observed in some chickens vaccinated with GX0101 Δmeq-BAC.On the other hand,compared with CVI988 /Rispens,the reconstruction of GX0101 Δmeq-BAC in the body is a prerequisite for access to protection.Therefore,there is a blank period after immunization,which provides a chance for infection with the wild Marek＇s disease virus.