猪繁殖与呼吸综合征病毒重组毒株GX-C4CG6致病性探究

Investigation on Pathogenicity of Recombinant Strain GX-C4CG6 of Porcine Reproductive and Respiratory Syndrome Virus

为评估猪繁殖与呼吸综合征病毒(PRRSV)重组毒株GX-C4CG6对小猪的致病性,选择PRRSV抗原、抗体均为阴性的小猪进行攻毒试验,然后通过攻毒后猪只体温变化及死亡情况、临床症状评分、血清抗体变化、攻毒后平均日增重、解剖后肺脏眼观及显微病理变化、血清/肺脏病毒拷贝数等指标,对该毒株致病性进行评估。结果显示:GX-C4CG6毒株攻毒组有4头猪出现发烧,平均体温在攻毒后第12、13天大于40℃,最高体温达40.4℃,未出现死亡;被攻毒猪仅表现轻微减料,未表现出明显的呼吸障碍;攻毒后7 d,攻毒组猪只抗体开始转阳,至攻毒后14 d,攻毒组猪只ELISA抗体S/P平均值达最高;攻毒组在攻毒后第1周和对照组平均日增重差异不显著,至第2周差异显著(P<0.05),攻毒组显著低于对照组;被攻毒猪出现肺脏间质性肺炎,血清和肺脏病毒拷贝数浓度较高,分别达9.2×10^(5)和1.6×10^(7)copies/mL。结果表明,PRRSV GX-C4CG6毒株对小猪表现温和致病性。本研究为PRRSV重组毒株流行的控制提供了基础资料。

In order to evaluate the pathogenicity of recombinant strain GX-C4CG6 of porcine reproductive and respiratory syndrome virus(PRRSV)on piglets,piglets negative for PRRSV antigen and antibody were selected for a challenge test,then the pathogenicity of GX-C4CG6 strain was evaluated according to the indicators such as changes in body temperature and mortality,clinical symptom scores,changes in serum antibodies,daily weight gain after challenge,visual and microscopic pathological changes in lungs after autopsy,and serum/lung virus load.The results showed that four pigs in the challenge group presented with symptom of fever,with an average body temperature exceeding 40℃on the 12th and 13th days,and a maximum of 40.4℃,but no death was found;the challenged pigs were only found with slight reduction in feed intaking rather than obvious respiratory disorders.On the 7th day,the antibodies in challenged pigs began to turn positive,on the 14th day,their average S/P value of ELISA antibodies reached the highest;the difference in average daily weight gain between the challenge group and the control group was not significant in the first week,but significant in the second week(P<0.05),which was obviously higher in the control group compared to the challenge group;and pulmonary interstitial pneumonia appeared in the challenged pigs,and virus load in serum and lung samples were relatively high,reaching 9.2×10^(5)and 1.6×10^(7)copies/mL,respectively.In conclusion,there was mild pathogenicity of PRRSV GX-C4CG6 strain to piglets.General data was provided for control of PRRSV recombinant strains.