猪伪狂犬病病毒变异株R13028株生物学特性及致病性的研究

Biological characteristics and pathogenicity of pseudorabies variant virus R13028 strain

为了解天津地区猪伪狂犬病病毒(pseudorabies virus,PRV)的流行情况,2013年从疑似PRV病例中分离纯化获得一株野毒株(R13028株),对其g C基因进行测序及分析,并研究病毒的细胞增殖特性和致病性。结果显示,R13028株与参考毒株相比在139位至189位缺失51 bp核苷酸,遗传进化分析显示该毒株与中国分离株的同源性高于欧美毒株,属于基因Ⅱ型,它与LA株的核苷酸同源性最高为99.7%。R13028株可在PK-15、BHK-21、Marc-145、Vero和ST细胞增殖,TCID_(50)测定结果表明ST细胞和PK细胞更适于R13028株的增殖。将PRV R13028株和经典强毒株SC株接种7周龄BALB/c小鼠后LD50分别为1×10^(4.5)TCID_(50)和1×10^(4.0)TCID_(50)。将两个毒株以1×10^(6)TCID_(50)剂量经滴鼻途径分别接种6周龄和9周龄猪,发现SC株(5/6头死亡)对猪的致死性高于R13028株(2/6头死亡)。但R13028株感染后猪体温升高和神经症状更为明显,试验猪发病和死亡时间早于SC株。本研究为猪伪狂犬病病毒的致病机制及防控研究提供了一定的理论依据。

In order to investigate the characteristics of porcine pseudorabies virus(PRV)in Tianjin,a PRV field strain(R13028)was isolated from suspicious PRV samples.The g C gene of isolated strain was sequenced and analyzed,and the biological characteristics and pathogenicity of viruse were studied.The results indicated that the g C gene of the R13028 strain contains 51 bases deletion at positions139—189,The phylogenetic analysis showed that the homology between the strain and the Chinese strain was higher than that of the European and American strains.It belonged to genotypeⅡ,and the highest nucleotide homology with LA strain was 99.7%.The R13028 strain could proliferate in PK-15,BHK-21,Marc-145,Vero and ST cells.The results of TCID_(50)showed the ST and PK-15 cell line were more suitable for enrichment culture of PRV R13028.In 7-week-old BALB/c mice,the 50%lethal dose(LD50)of R13028 strain and SC strain were 1×10^(4.5)TCID_(50)and 1×10^(4.0)TCID_(50),respectively.Groups of 6-week-old and 9-week-old pigs were inoculated i.n.with 1×10^(6.0)TCID_(50)of the two strains.The results showed that the PRV SC strain(5/6 death)displayed higher mortality than the PRV R13028 strain(2/6 death)to two group pigs.However,the temperature and neurological symptoms of R13028 strain infected pigs were more obvious,the onset and death time of experimental pigs were earlier than that of SC strain.This study could provide a theoretical basis for the prevention and control of pseudorabies and vaccine research.