猪繁殖与呼吸综合征病毒基因2型类NADC30毒株感染模型的建立

Investigation on the infection model for NADC30-like strains of porcine reproductive and respiratory syndrome virus genotype 2

本研究旨在建立猪繁殖与呼吸综合征病毒(PRRSV)类NADC30流行毒株的感染模型。选择田间分离的类NADC30毒株PRRSV/GSWW/2018作为攻毒毒株,采用滴鼻、肌肉注射和皮下注射这3种方式进行感染,攻毒剂量为接种细胞培养病毒液2 m L/头(10~6TCID50/m L),每组3头猪。攻毒后采集血液、鼻拭子、肛拭子检测病毒血症与排毒情况,每天检测体温变化,记录增重与发病死亡情况,死亡猪及时进行剖检,观察肺组织病变情况,根据以上指标评价感染模型是否建立成功。结果显示,滴鼻与肌肉注射组在感染后第24小时出现发热症状,持续约1周时间;感染后第48小时病毒血症达峰值、并持续至死亡;滴鼻与肌肉注射攻毒组猪的体重下降,并表现出明显的临床症状与排毒现象,滴鼻组、肌肉注射组均100%死亡,皮下注射组与未感染对照组均表现正常。上述结果表明,PRRSV/GSWW/2018株通过肌肉注射或滴鼻方式均可成功感染仔猪,并表现出明显的临床症状,且有很强的致病性,表明感染模型建立成功,这为后续抗病毒药物筛选或疫苗研发奠定了良好基础。

The aim of this study was to establish an infection model for PRRSV new emerging NADC30-like strain to lay the foundation for vaccine and therapeutic drug screening.The PRRSV/GSWW/2018 strain is a NADC30-like virus strain isolated from one pig farm in Gansu province,which was selected as challenge virus strain to develop infection model.Total of 12 pigs was evenly separated into 4 groups,which were infected by nasal inhalation,intramuscular and subcutaneous injections of 2 mL cell cultured virus materials(contain 106TCID50/mL of the virus)with one group as normal control.Blood,nasalswabs and anal swabs were collected to detect viraemia and virus excretion.Body temperature and weight changes were detected every day,and pigs were anatomized after death to check lung lesions and virus persistence in different lymph nodes.The successfulness of the infection model was evaluated based on the above indexes.The results showed that pigs infected by the nasal and intramuscular routes began to have a fever at 24 hours post infection,which lasted for about 1 week;the viraemia peaked at 48 hours post infection and lasted until the death;all diseased pigs showed decreased body weight and typical PRRS clinical signs,and gradually died at 12 to 14th days post infection for the nasally and intramuscularly challenge groups.All pigs keep healthy state until the end of the experiment for the subcutaneous inoculated group and the uninfected control group.In conclusion,the PRRSV/GSWW/2018 strain could be lethal to piglets after challenge by intramuscular or nasal routes,and all pigs showed typical clinical symptoms and died within two weeks after virus challenge.The establishment of this challenge model for NADC30 like PRRSV strain laid a good foundation for the subsequent screening of antiviral drugs or vaccine development.