不同猪繁殖与呼吸综合征疫苗组合体液免疫效果评估OA

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-1 a 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.