多克隆抗体对猪繁殖与呼吸综合征的防治效果

目的观察猪繁殖与呼吸综合征病毒(Porcine reproductive and respiratory syndrome virus,PRRSV)多克隆抗体用于防治PRRS的效果。方法用PRRSV灭活疫苗2次基础免疫,PRRSV(NVDC-JXA1株)强毒C05代加强免疫长白仔猪,制备PRRSV多克隆抗体。以不同剂量的多抗免疫仔猪后,通过仔猪存活率、血清ELISA抗体效价及血清、肺、脑组织PRRSV基因评价多克隆抗体对PRRSV感染的预防和治疗作用。结果仔猪按0.5ml/kg体重接种多抗进行预防,再经PRRSV(NVDC-JXA1)株强毒(3×105.5TCID50)攻击,具有一定的预防作用,存活率为5/7;经NVDC-JXA1株强毒(3×105.5TCID50)感染后,分别按0.8ml/kg和1.0ml/kg剂量,连续注射3次进行治疗,存活率分别为5/7和7/7,但在注射1.0ml/kg的猪中,仍有部分猪血清(4/7)和肺(2/7)PRRSV基因阳性。结论高剂量的多克隆抗体(ELISAS/P>3,0.5ml/kg以上)对仔猪抵抗PRRSV感染具有一定的预防和治疗作用,经多克隆抗体预防或治疗后无临床症状的猪仍可能带毒。

Preventive and Therapeutic Effects of Polyclonal Antibody on Porcine Reproductive and Respiratory Syndrome

Objective To observe the preventive and therapeutic effects of polyclonal antibody against porcine reproductive and respiratory syndrome virus(PRRSV) on PRRS.Methods Changbai piglets were preliminarily immunized with inactivated PRRSV vaccine and boosted with virulent PRRSV NVDC-JXA1 strain passage C05 to prepare the polyclonal antibody against PRRSV.The prepared polyclonal antibody was used for immunization of piglets,at various dosages,and its prevention and therapeutic effects were evaluated with the survival rate,serum ELISA antibody titer as well as the PRRSV gene in serum,lung and brain tissues.Results The survival rate of piglet immunized with the prepared polyclonal antibody at a dosage of 0.5 ml /kg body weight after challenge with 3 × 105.5 TCID50 of NVDC-JXA1 strain was 5 /7,indicating a certain preventive effect of antibody.The survival rates of piglets challenged with 3 × 105.5 TCID50 of NVDC-JXA1 strain were 5 /7 and 7 /7 after treatment with the prepared polyclonal antibody at dosages of 0.8 and 1.0 ml /kg body weight for 3 times respectively.However,4 /7 and 2 /7 of piglets treated with the antibody at a dosage of 1.0 ml /kg body weight were positive for PRRSV gene in their sera and lungs respectively.Conclusion The polyclonal antibody with an ELISA S /P value of more than 3 at a dosage of more than 0.5 ml /kg body weight showed a certain preventive and therapeutic effects on PRRSV infection in piglets.However,the asymptomatic piglets after immunization or treatment with the prepared antibody might still carry PRRSV.