2株猪繁殖与呼吸综合征病毒的致病性分析

Pathogenic Analysis of Two Strains of Porcine Reproductive and Respiratory Syndrome Virus

为追踪猪繁殖与呼吸综合征病毒(porcine reproductive and respiratory syndrome virus,PRRSV)分离株的变异特点,本研究于2016年从河北和福建疑似猪繁殖与呼吸障碍综合征(PRRS)发病猪场采集病料,接种Marc-145细胞,产生合胞体样细胞病变,RT-PCR和间接免疫荧光试验鉴定为HP-PRRSV,将其分别命名为PRRSV CZ16A和NP16A。为研究PRRSV分离株CZ16A和NP16A对猪的致病性,将分离毒株经噬斑纯化后分别接种PRRSV抗原、抗体双阴性的60日龄健康仔猪,通过临床观察、解剖病理变化及病毒血症检测等指标初步探讨两株PRRSV的致病性。结果表明,分离株CZ16A和NP16A感染猪后均能够在动物体内复制,并引起体温升高,但两株PRRSV分离株均未引起试验动物的发病和死亡,剖检结果显示NP16A分离株能引起动物肺部实变、淋巴结肿大,其毒力比CZ16A分离株稍强。

Samples of sick pigs suspected of porcine reproductive and respiratory syndrome （PRRS） infection were collected from Hebei and Fujian provinces in China in 2016. Studies were carried out to investigate the variation characteristics of the isolated virus strains. The virus iso- lates were propagated in Marc-145 cells and caused syncytial cytopathic effect. RT-PCR and indi- rect fluorescent assay （IFA） results showed that the isolates were HP-PRRSV and hence desig- nated as PRRSV CZ16A and NP16A, respectively. In order to study the pathogenicity of CZ16A and NP16A, the isolated strains were purified by plaque-isolation, and then inoculated to 60- days-old healthy pigs, which were negative in both of PRRSV infection and antibody. Clinical ob- servation, histopathological changes and viremia detection were carried out to evaluate the patho- genicity of these two strains of PRRSV. Results showed that both isolates could replicate in pigs and cause a high body temperature, but these two strains of PRRSV isolates could not cause mor- bidity or mortality in experimental animals. Autopsy results also showed that NP16A could cause consolidation of the lung, lymph node enlargement in tested animals, suggesting that its virulence was a little stronger than CZ16A.