敲除Meq基因的重组鸡马立克氏病毒与CVI988/Rispens疫苗株免疫保护效力的比较

Comparison of immunoprotection between vaccination with meq-deleted Marek s disease virus and vaccine strain CVI988/Rispens

摘要:

摘要:【目的】比较敲除meq基因的马立克氏病毒(MDV)与标准疫苗株CVI988/Rispens对MDV超强毒GX0101攻毒的免疫保护作用。【方法】本实验将1日龄SPF鸡120只随机分成4 组，每组30只，分别饲养在正压过滤空气的SPF动物饲养隔离罩内。1日龄时，第1组鸡以2000PFU/只的剂量颈部皮下接种SC9-1;第2组鸡以2000PFU/只的剂量颈部皮下接种CVI988/Rispens;第3、4组为不免疫攻毒对照组。免疫接种后5 d后，第1、2、3组分别以2000PFU/只的剂量腹腔接种MDV GX0101。饲养至90日龄，记录死亡情况，对死亡鸡只剖检，并取疑似马立克特有病变脏器做病理切片。期间，检测不同免疫状态下病毒GX0101的增殖动态以及禽流感、新城疫灭活苗在鸡体诱导产生抗体的水平。对含有MDV母源抗体的海蓝褐鸡的试验方案与SPF鸡一致。【结果】SC9-1株免疫对感染MDV GX0101攻击SPF鸡、海兰褐鸡均提供100%的免疫保护作用;CVI988/Rispens对SPF鸡、海兰褐鸡分别提供86.7%、93%的免疫保护作用。未免疫SPF鸡攻毒组死亡率为53.3%，肿瘤率为16.7%;未免疫海兰褐鸡攻毒组死亡率为36.7%，肿瘤率为6.67%;相比，空白对照组鸡只没有任何病变及死亡。荧光定量结果显示，淋巴细胞和羽毛囊DNA中，SC9-1免疫组鸡体内GX0101的病毒拷贝数显著低于CVI988/Rispens免疫组。血凝抑制试验结果显示，SC9-1 免疫攻毒组鸡的产生的AIV、NDV抗体水平高于CVI988/Rispens免疫攻毒组。【结论】SC9-1株免疫无论在SPF鸡还是含有MDV母源抗体的海兰褐鸡均能提供比CVI988/Rispens 更好的免疫保护效果。

Abstract:

Abstract:［Objective］ To evaluate and compare the immunoprotection between a meq-deleted Marek s disease virus (MDV) and CVI988/Rispens against MDV very virulent strain GX0101．［Methods］ In total 120 one-day-old SPF chickens were divided into 4 groups (30 each) and kept in 5 isolators with positive pressure-filtered air．At 1 day of age，2000 PFU of SC9-1 was inoculated subcutaneously into each bird in group 1;2000 PFU of commercial vaccine CVI988/Rispens was inoculated subcutaneously into each bird in group 2．No viral challenge was made in group 3 and 4 as controls．Five days later chickens in group 1，2，3 were challenged intra-abdominally with 2000 PFU of very virulent MDV strain GX0101．During 90 days after challenge，all dead birds were recorded and checked for necropsy．The tumorsuspected tissues were examined by histopathological biopsy．The antibody titers induced by AIV and NDV vaccination and propagation dynamics of MDV GX0101 were detected．At the same time，parallel tests were performed on Hy-Line Brown chickens containing MDV maternal antibody．［Results］ SC9-1 stain provided 100% protective efficiency against very virulent GX0101 challenge in SPF and Hy-Line Brown chickens．CVI988/Rispens provided 86.7% protective efficiency against very virulent GX0101 challenge in SPF chickens and 93% in Hy-Line Brown chickens．Challenge with GX0101 caused 53.3% mortality and 16.7% of birds with gross tumors in SPF chickens while there was 36.7% mortality and 16.7% of birds with gross tumors in Hy-Line Brown chickens，and there was no tumor lesion in histopathological biopsy in control group．The results of qPCR demonstrated that the copies of GX0101 viral genomes in SC9-1 vaccinated chickens was lower than CVI988/Rispens vaccinated chickens in lymphocyte and feather follicle DNA．The results of hemagglutination inhibition test demonstrated that antibody titers of AIV and NDV was higher in SC9-1 vaccinated chickens than that in CVI988/Rispens vaccinated chickens．［Conclusion］SC9-1 stains immunoprotection against MDV is more effective than CVI988/Rispens strain s both in SPF chickens and commercial Hy-Line Brown chickens containing maternal antibody．