BACKGROUND Virus neutralization test (VNT) is widely used for serological survey of classical swine fever (CSF) and efficacy evaluation of CSF vaccines. However, VNT is a time consuming procedure that requires cell culture and live virus manipulation. C-strain CSF vaccine is the most frequently used vaccine for CSF control and prevention. In this study, we presented a neutralizing monoclonal antibody (mAb) based competitive enzyme-linked immunosorbent assay (cELISA) with the emphasis on the replacement of VNT for C-strain post-vaccination monitoring. RESULTS One monoclonal antibody (6B211) which has potent neutralizing activity against C-strain was generated. A novel cELISA was established and optimized based on the strategy that 6B211 can compete with C-strain induced neutralizing antibodies in pig serum to bind capture antigen C-strain E2. By testing C-strain VNT negative pig sera (n = 445) and C-strain VNT positive pig sera (n = 70), the 6B211 based cELISA showed 100% sensitivity (95% confidence interval: 94.87 to 100%) and 100% specificity (95% confidence interval: 100 to 100%). The C-strain antibody can be tested in pigs as early as 7 days post vaccination with the cELISA. By testing pig sera (n = 139) in parallel, the cELISA showed excellent agreement (Kappa = 0.957) with VNT. The inhibition rate of serum samples in the cELISA is highly correlated with their titers in VNT (r2 = 0.903, p < 0.001). In addition, intra- and inter-assays of the cELISA exhibited acceptable repeatability with low coefficient of variations (CVs). CONCLUSIONS This novel cELISA demonstrated excellent agreement and high level correlation with VNT. It is a reliable tool for sero-monitoring of C-strain vaccination campaign because it is a rapid, simple, safe and cost effective assay that can be used to monitor vaccination-induced immune response at the population level.

中文翻译：

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基于中和性单克隆抗体的竞争性ELISA，用于经典猪瘟C株疫苗接种后监测。

背景技术病毒中和试验（VNT）被广泛用于经典猪瘟（CSF）的血清学调查和CSF疫苗的功效评估。但是，VNT是一项耗时的过程，需要进行细胞培养和活病毒操作。C株CSF疫苗是控制和预防CSF的最常用疫苗。在这项研究中，我们提出了一种基于中和性单克隆抗体（mAb）的竞争性酶联免疫吸附测定（cELISA），重点是用于C株疫苗接种后监测的VNT替代。结果产生了一种对C株具有强力中和活性的单克隆抗体（6B211）。基于6B211可与猪血清中C株诱导的中和抗体竞争以结合捕获抗原C株E2的策略，建立并优化了新型cELISA。通过测试C株VNT阴性猪血清（n = 445）和C株VNT阳性猪血清（n = 70），基于6B211的cELISA显示出100％的灵敏度（95％的置信区间：94.87至100％）和100％特异性（95％置信区间：100至100％）。最早在接种cELISA后7天，即可在猪中测试C株抗体。通过并行测试猪血清（n = 139），cELISA与VNT显示出极好的一致性（Kappa = 0.957）。cELISA中血清样品的抑制率与其在VNT中的滴度高度相关（r2 = 0.903，p <0.001）。另外，cELISA的测定内和测定间显示出可接受的重复性，且变异系数（CV）低。结论新型cELISA与VNT表现出极好的一致性和高度相关性。