【作者】 王进；

【导师】 高崧；

【作者基本信息】 扬州大学 ， 预防兽医学， 2019， 硕士

【摘要】 猪伪狂犬病(Pseudorabies,PR)是由伪狂犬病病毒(Pseudorabies virus,PRV)引起的多种家畜及野生动物共患的一种广泛流行的急性传染病,以发热、奇痒(除猪外)、呼吸及神经系统疾病为主要特征,此外妊娠母猪极易发生流产或死胎。该病在我国许多猪场均有流行,迄今,尚无治疗PRV的有效药物,因此控制该病发生和流行的主要措施之一为免疫接种。但是疫苗接种并不能完全阻止疾病的发生,自2011年下半年以来,我国多地接种疫苗的猪群中发生了猪伪狂犬病的流行,新出现的伪狂犬病病毒变异株对各年龄段的猪均可致病,暗示现有某些商品疫苗似乎不能对当前流行的变异株提供临床保护,从而使我国养猪行业面临较大风险。1.猪伪狂犬病病毒的分离及部分基因序列分析2019年初,江苏某猪场爆发猪伪狂犬病,从发病猪的病料中分离出1株猪伪狂犬病病毒变异株,命名为XJ9。对该毒株的4个糖蛋白基因gE、gC、gI、gB和毒力基因TK的全序列分析,结果显示该毒株与本室于2014年从同一猪场分离的XJ5株存在微小变异。研究结果为持续跟踪同一猪场猪伪狂犬病病毒变异株的演变提供了参考。2.Bartha-K61 疫苗和 rPRV/XJ5-gI-/gE-/TK-疫苗对 vPRV strain XJ5 非致死性攻毒的免疫保护作用以实验室构建的猪伪狂犬病病毒变异株PRV-XJ5的gE/gI/TK三基因缺失株,以及商品苗Bartha-K61为材料,进行2种疫苗对生长猪的免疫保护试验,比较不同剂量的Bartha-K61疫苗和rPRV/XJ5 gE/gI/TK三基因缺失株对变异株PRV-XJ5非致死性攻击的免疫保护效果。通过对免疫后的血清抗体和攻毒后各试验组猪的临床症状、增重、咽拭子和肛拭子排毒、大体病理学、组织病理学等的检测及观察,全方位评价Bartha-K61疫苗和rPRV/XJ5 gE/gI/TK三基因缺失株的免疫保护效果。试验结果表明,低剂量的Bartha-K61疫苗(每头猪103,104TCID50)免疫猪的增重、排毒、病理组织学学指标均显著低于高剂量Bartha-K61疫苗和rPRV/XJ5 gE/gl/TK三基因缺失株免疫猪(每头猪105TCID50),且高剂量的2种疫苗免疫猪的增重、组织学观察等方面与健康对照猪相当。因此,选择合适剂量Bartha-K61疫苗免疫仍然是当前控制变异株危害的理性选择。需要强调的是,rPRV/XJ5 gE/gl/TK三基因缺失株疫苗在相同剂量前提下,与Bartha-K61疫苗的免疫保护效果相近,提示在防控由变异株引起的猪伪狂犬病的流行中多了一项选择。更多还原

【Abstract】 Pseudorabies(PR)is a widely-distributed acute infectious disease in livestocK and wild animals caused by Pseudorabies virus(PRV),characterized by fever and itchy(except pigs)in diseased animals.Respiratory and neurological signs are the also common features of PR,and pregnant sows are prone to abortion or stillbirth.So far,there are no effective drugs for treating PR,so one of the effective measures to prevent and control the disease is vaccination intervention.However,vaccination is not an omnipotent strategy.Since 2011,PR has been reemergent in many vaccinated pig populations of China.The reemergent PR has been confirmed to be caused by a Kind of variant PRV(vPRV).with pathogenicity to pigs of all ages.It implied that the partial commercial PR vaccines seem not to protect pigs from vPRV infection,posing a potential threat to the pig industry in China.1.Isolation and identification of a pseudorabies virus isolate and analysis of its selected genesIn early of 2019,an outbreaK of PR befell a pig farm located in Jiangsu province.A vPRV strain,namely vPRV XJ9,was isolated and identified.Five glycoprotein coding genes gE,gC,gI,gD,gB and a virulence gene TK of the strain were amplified and sequenced,the results showed that the tested genes of strain vPRV XJ9 exhibited a minute evolution compared with the vPRV XJ5 strain,which isolated from the same farm in 2014 by our laboratory.It is of significance to trace the vPRV evolution in one pig farm under both field and immune pressure conditions.2.Bartha-K61 vaccine and rPRV-gI-/gE-/TK-vaccine protect pigs from vPRV strain XJ5 sublethal challengeA number of studies have proved that the PR reemergence since the late of 2011 in China is due to the highly pathogenic,antigenic variant PRV(vPRV)strains,and how to prevent and control the recurrence of the disease in China has been put on the agenda.In a previous study,we have proved that a commercial Bartha-K61 vaccine protects growing pigs against lethal challenge with an emerging vPRV strain XJ5.In this study,Bartha-K61 vaccine with different doses(50%tissue culture infectious dose,TCID50),and a prototype rPRY-gI-/gE-/TK-vaccine strain derived from vPRV strain XJ5 constructed in the laboratory were used to evaluate the immune protection effect in growing pigs against a sublethal challenge with the vPRV strain XJ5.Humoral immunity response,clinical signs,body weight,virus shedding and pathology were assessed in commercial pigs.The results showed that the low-doses(103,104 TCID50 per animal)Bartha-K61 vaccine could not effectively against vPRV strain XJ5 sublethal challenge,while the high-dose(105 TCID50 per animal)of either Bartha-K61 vaccine or rPRV-gI-/gE-/TK-prototype vaccine administered pigs could effectively against vPRV strain XJ5-sublethal challenge.In addition,pigs vaccinated with the high-dose of either Bartha-K61 vaccine or rPRV-gI-/gE-/TK-prototype vaccine showed no difference between each other in humoral immune response,clinical symptoms,weight gain,virus shedding and gross or histological lesions after the sublethal challenge with vPRV strain XJ5.Therefore,we can draw a conclusion that the either Bartha-K61 vaccine or rPRV-gI-/gE-/TK-prototype vaccine with a dose of 105 TCID50 exerted a promising protection to pigs against a sublethal challenge with the vPRV strain XJ5,while low doses,e.g.103,104 TCID50 per animal,of Bartha-K61 vaccine were not able to protect pigs against a sublethal challenge with the vPRV strain XJ5.The results of this study provide helpful information in vaccination intervention and ultimate eradication of Pseudorabies caused by the emerging vPRV strains originated in China.更多还原