基因组学与应用生物学

伪狂犬病(Pseudorab ies PR)是由伪狂犬病毒(PRV)引起的,可导致多种家畜和野生动物以发热、奇痒(猪除外)及脑髓炎为主要症状的急性传染病。猪是该病毒的中间宿主和传染源,感染后可引起妊娠母猪发生严重的繁殖障碍造成死胎、流产和木乃伊胎,患病仔猪表现为神经症状和呼吸道病,多以死亡告终。在规模化、集约化、现代化高密度养猪地区,PRV可在猪群间不断传播,是危害我国养猪业的一个重要传染病。用疫苗进行免疫接种是预防、甚至消灭伪狂犬病的根本措施。目前伪狂犬病疫苗在我国应用最多的是Bartha-K 61株,该疫苗是20世纪60年代匈牙利Bartha等人将野毒株用鸡胚成纤维细胞反复传代而获得的一个人工致弱疫苗株,该毒株呈现gE基-因缺失表型,其毒力大大减弱,免疫原性很好,是世界上公认的优良疫苗株。我们以Bartha-K61株为载体构建了表达猪繁殖与呼吸综合征病毒(PRRSV)CH-1a株GP5基因的重组伪狂犬病病毒(rPRV-GP5),但GP5基因的插入是否会改变伪狂犬病病毒Bartha-K61株对伪狂犬病的免疫保护效力?为此本研究通过测定重组伪狂犬病毒(rPRV-GP5)对伪狂犬病的最小免疫剂量,评价rPRV-GP5对伪狂犬病的保护效力。24只5⁶月龄PRV阴性健康绵羊随机分成6组,每组4只,其中1组为生理盐水对照组,其余5组分别后腿肌注重组伪狂犬病毒(rPRV-GP5)冻干疫苗(病毒含量为5×106.0TCID50/mL)5×104.0TCID50/只、5×103.0TCID50/只、5×102.0TCID50/只、5×101.0TCID50/只和5TCID50/只,免疫后15 d每只绵羊肌注伪狂犬病毒猪源强毒S株1000 LD50。结果表明:对照组和5TCID50/只组的全部绵羊攻毒后4⁵ d均出现典型伪狂犬病症状并死亡,5×101.0TCID50/只组4只绵羊中有2只发病并死亡,其余各组全部保护。结论:重组伪狂犬病毒(rPRV-GP5)对绵羊最小免疫剂量为100 TCID50/只,GP5基因的插入没有影响伪狂犬弱毒疫苗Bartha-K61株的免疫原性。

To test the minimum dose of protection of the recombinant pseudorabies virus(PRV) expressing porcine reproductive and respiratory syndrome virus(PRRSV) GP5(rPRV-GP5) developed earlier against pseudorabies,twenty-four 5⁶-month-old sheep were randomly divided into six groups,each group of 4 sheep,groups of 1⁵ were immunized intramuscularly 5×10⁴.0 TCID_50、5×10³.0 TCID_50、5×10².0 TCID_50、5×10¹.0 TCID_50respectively and 5 TCID_50,respectively and group 6 was served as control.Fifteen days after immunization,all sheep of groups 1⁶ were injected by intramuscular with 10³ LD_50 of the highly virulent PRV S strain of porcine origin.The results showed that vaccinated sheep in groups 1³ were complete protected from PRV,two sheep in group 4 also were protected,all sheep in group 5 and 6 died,the minimum dose of protection of rPRV-GP5 against pseudorabies in sheep is 100 TCID_50.