应用荧光定量RT-PCR方法检测PRRSV变异株在仔猪体内动态分布

The dynamic distribution of PRRSV mutant strain in infected piglets by the fluorescent quantitative RT-PCR

为进一步了解高致病性猪繁殖与呼吸综合征病毒(PRRSV)变异株(HuN4株)在体内的动态分布规律和特点,探讨病毒对组织器官的嗜性,本研究将HuN4株和细胞传代致弱毒株HuN4-F65人工感染40日龄健康仔猪,分别于感染后1d、3d、5d、7d、10d、14d、21d和28d各迫杀2头,并应用建立的荧光定量RT-PCR方法对脑、颌下淋巴结、扁桃体、肺脏、肝脏和十二指肠等组织及血清中的PRRSV进行定量检测。结果显示:感染后HuN4组各器官病毒载量比HuN4-F65组高100倍,病毒载量峰值期出现在感染后7d,随后呈下降趋势。HuN4株在仔猪体内分布广泛,在21d的试验期内持续存在,并且各器官的病毒载量呈正态分布规律;而HuN4-F65株血清病毒载量较低,并且集中在单核巨噬细胞相对密集的扁桃体和颌下淋巴结,与HuN4株主要嗜性器官肺脏相比发生了改变。

To understand the kinetics and distribution of highly pathogenic porcine reproductive and respiratory syndrome virus （PRRSV） mutant strain （HuN4 strain） in piglets,forty-day-old healthy piglets were inoculated with the virulent HuN4 strain or the attenuated strain HuN4-F65,and slaughtered at 3,5,7,10,14,21 and 28 days post-inoculation （dpi）,respectively. The brain,submandibular lymph node,tonsil,lung,liver,duodenum and serum samples were collected and detected by real-time RT-PCR. The results showed that the viral load in HuN4 infected group was significantly higher than that in HuN4-F65 group,which peaked on 7 dpi,and decreased at the later stage. The HuN4 strain was widely distributed during entire 21 dpi in various organs,especially in the lung. In contrast,the serum viral load in HuN4-F65 group appeared lower,and mainly in the tonsil and submandibular lymph nodes where monocyte-macrophage cells are relatively dense. These results indicated that the HuN4 viral tropism to the lung and other organs had sustained significant changes after attenuation.