高水平母源抗体仔猪接种猪繁殖与呼吸综合征弱毒活疫苗的免疫效果分析

Evaluation of the efficacy of porcine reproductive and respiratory syndrome attenuated live vaccine in the piglets with high level maternally-derived antibody

为评估猪繁殖与呼吸综合征(PRRS)弱毒活疫苗的免疫效果,本研究于规模猪场选取具有母源抗体的仔猪,接种PRRS弱毒活疫苗后不同时间采集血清,应用RT-PCR检测PRRS病毒(PRRSV)核酸,应用N-ELISA和G-ELISA两种试剂盒检测PRRSV抗体。结果显示,在免疫接种后60 d内可在实验仔猪血清中检测到疫苗株核酸,而在整个实验期间未能检测到野毒株核酸。仔猪在免疫前具有较高的母源抗体,阳性率达到100%,此后逐渐下降,在免疫后第28 d/60 d(第2次试验/第1次试验)降到低点后又稳步升高,从免疫后第60 d/90 d到150 d试验结束时阳性率均达到100%。应用两种ELISA试剂盒同时检测329份血清样品,检测结果的符合率为96.96%;配对χ~2检验,p>0.05,两者差异不显著;Kappa值为0.81,属于极强一致性;两者相关系数r为0.794,具有显著线性相关。本研究结果表明,高水平母源抗体猪群接种弱毒活疫苗后取得良好的免疫效果,可选用N-ELISA或G-ELISA试剂盒进行免疫效果评估。

To evaluate the efficacy of porcine reproductive and respiratory syndrome （PRRS） attenuated live vaccine, piglets with maternally-derived antibody were selected from a large-scale pig farm and vaccinated with the PRRS vaccine. Sera were collected on different days post vaccination to detect PRRS virus nucleic acid by RT-PCR and detect PRRSV antibody by ELISA using N-ELISA and G-ELISA kits. The results showed that vaccine virus nucleic acid were detected until 60 days post vaccination （dpv）, but no wild-type PRRSVnucleic acid was detected during the experiment. All piglets had high level maternally-derived antibody and the positive rate was 100% on 0 dpv, but the rate was gradually fall afterward until 28 days/60 days （2nd/lst experiment）, then increased rapidly and 100% seroconverted from 60 days/90 days to the end of the experiment on 150 dpv. A total of 329 serum samples were detected respectively by the two ELISA kits and the coincidence rate of the results was 96.96%. The p value of Х2 test was higher than 0.05 with no significant difference between two kits. The Kappa value was 0.81 with strong consistence. The correlation coefficient was 0.794 with significant linear correlation. The results indicated that the piglets with high level of maternally-derived antibody were able to acquire efficient protection after vaccination with attenuated live vaccine, and N-ELISA and G-ELISA kits could be used to evaluate the immune efficacy.