不同猪繁殖与呼吸综合征疫苗组合体液免疫效果评估

Evaluation of Humoral Immune Effect of Different Vaccine Combinations for PRRS

为了比较不同猪繁殖与呼吸综合征(PRRS)疫苗不同免疫程序对体液免疫效果的影响,本试验选择新引进猪繁殖与呼吸综合征病毒(PRRSV)抗原和抗体均为阴性后备母猪的3个猪场,将各场内猪只按体重分为3个阶段:7~20、20~35和35~50 kg,各场分别从中选取20头猪,共180头猪。每场选用1种免疫方案,第1组混合疫苗组,为首次免疫PRRS弱毒疫苗(CH-1R株),28 d后加强免疫PRRS灭活疫苗(CH-1a株);第2组弱毒疫苗组,为2次均免疫PRRS弱毒疫苗;第3组灭活疫苗组,为2次均免疫PRRS灭活疫苗。疫苗首次免疫后14、28、42和56 d采集猪血清,进行特异性PRRSV ELISA(N蛋白)检测和中和抗体评价;首次免疫后14和28 d采集猪血液,进行PRRSV实时荧光定量PCR(RT-qPCR)检测血液内是否存在PRRSV;统计试验猪分娩后头胎的活仔数、断奶仔猪数和窝均总仔数,进行临床数据比较分析。结果显示,35~50 kg体重阶段猪只接种疫苗后ELISA检测抗体水平增高较其他2个阶段更明显。混合疫苗组在免疫56 d时血清ELISA阳性率为100%,且ELISA结果极显著高于弱毒疫苗组和灭活疫苗组(P<0.01)。尽管各组没有产生特异性抗NADC30-like毒株的中和抗体,但针对PRRSV经典和高致病性毒株的中和抗体保护效价结果显示,混合疫苗组在免疫56 d时中和抗体效价极显著高于弱毒疫苗组和灭活疫苗组(P<0.01);RT-qPCR检测未发现阳性猪;各组试验猪分娩后头胎的活仔数、断奶仔猪数和窝均总仔数之间差异不显著(P>0.05)。结果表明,混合疫苗组对体液免疫的促进效果显著优于弱毒疫苗组和灭活疫苗组。该试验为临床正确选择PRRS疫苗免疫方案提供了科学数据。

In order to compare the impact of different vaccine combinations for porcine reproductive and respiratory syndrome(PRRS)on humoral immune effects,this study selected three pig farms with newly introduced porcine reproductive and respiratory syndrome virus(PRRSV)antigens and antibodies-negative sow herds.Pigs within each farm were divided into three stages by weight:7-20,20-35,and 35-50 kg,and twenty pigs were selected from each farm,making a total of 180 pigs.Each farm adopted one immunization scheme:the first group was the Mixed vaccine group,with the initial immunization of PRRS attenuated vaccine(CH-1R strain)followed by a booster immunization of PRRS inactivated vaccine(CH-1a strain)28 days later;the second group was the Attenuated vaccine group,received two immunizations of PRRS attenuated vaccine;the third group was the Inactivated vaccine group,received two immunizations of PRRS inactivated vaccine.Serum samples were collected at 14,28,42,and 56 days after the first immunization for specific PRRSV ELISA(N protein)testing and neutralizing antibody evaluation.Blood samples were collected at 14 and 28 days after the first immunization for PRRSV real-time fluorescence quantitative PCR(RT-qPCR)to detect the presence of PRRSV in the blood.Clinical data,including the number of live piglets,weaned piglets,and total piglets per litter,were collected after the first littering,and comparative analysis was performed.The results showed that pigs in the 35-50 kg weight stage had a more pronounced increase in antibody levels after vaccination compared to the other two stages.In the Mixed vaccine group,the serum ELISA positivity rate was 100%at 56 days of immunization,and the ELISA results were significantly higher than those in the Attenuated vaccine group and Inactivated vaccine group(P<0.01).Although no specific neutralizing antibodies against the NADC30-like strain were generated in all groups,the results of neutralizing antibody protection efficacy against classical and highly pathogenic PRRSV strains showed that the Mixed vaccine group had significantly higher neutralizing antibody titers at 56 days of immunization compared with the Attenuated vaccine group and Inactivated vaccine group(P<0.01).RT-qPCR testing did not detect positive pigs in any group.There were no significant differences in the number of live piglets,weaned piglets,and total piglets per litter among each group(P>0.05).The results indicate that the Mixed vaccine group has a significantly better promotion effect on humoral immunity compared with the Attenuated vaccine group and Inactivated vaccine group.This study provides scientific data for the correct selection of PRRS vaccine immunization schemes in clinical practice.