Introduction. PCV2 is a DNA virus that exists widely in pigs and has caused great economic losses to the pig industry worldwide. In the existing commercial PCV2 enzyme-linked immunosorbent assay (ELISA) kits both natural infection with PCV2 and vaccine immunization produce results that are positive for PCV2 Cap antibodies and therefore they cannot diagnose PCV2 infection in immunized pig farms. Aim. To establish a PCV2 non-structural protein antibody detection method that distinguishes between antibodies resulting from natural prior exposure (infection) and those induced by subunit vaccine immunization. Methodology. Based on the non-structural Rep′ protein, we established an indirect ELISA (iELISA) using sera from guinea pigs and piglets. Results. The results for iELISA for guinea pig serum showed that animals vaccinated with a whole-virus inactivated PCV2 vaccine had 100 % (10/10) Cap antibody positivity and 100 % (10/10) Rep′ antibody positivity. Guinea pigs vaccinated with a recombinant subunit PCV2 vaccine had 100 % (10/10) Cap antibody positivity, while no (0/10) guinea pigs were Rep′ antibody-positive. The combined detection results for the Rep′ iELISA and a PCV2 Antibody Test kit (Commercial) showed that pigs vaccinated with a whole-virus inactivated PCV2 vaccine or PCV2 SD/2017 had 100 % (5/5) Cap antibody positivity and 100 % (5/5) Rep′ antibody positivity. Pigs vaccinated with a recombinant subunit PCV2 vaccine had 100 % (5/5) Cap antibody positivity, while no (0/10) pigs were Rep′ antibody-positive. Conclusion. This paper describes an effective iELISA method that can distinguish natural infection with PCV2 (Cap and Rep positive) or inoculation with a whole-virus inactivated vaccine (Cap and Rep positive) from subunit vaccine immunization (Cap-positive, Rep-negative). These comparative assays could be very useful in the control of PCV2 in pig herds.

中文翻译：

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建立Rep'蛋白抗体检测方法以区分PCV2自然感染与亚单位疫苗免疫。

介绍。PCV2是一种DNA病毒，广泛存在于猪中，已给全世界的养猪业造成了巨大的经济损失。在现有的商用PCV2酶联免疫吸附测定（ELISA）试剂盒中，PCV2的自然感染和疫苗免疫均产生PCV2 Cap抗体阳性的结果，因此，它们无法在免疫猪场中诊断PCV2感染。目标。建立一种PCV2非结构蛋白抗体检测方法，该方法可区分自然先前暴露（感染）产生的抗体和亚单位疫苗免疫诱导的抗体。方法。基于非结构性Rep'蛋白，我们使用豚鼠和仔猪的血清建立了间接ELISA（iELISA）。结果。豚鼠血清iELISA的结果表明，用全病毒灭活的PCV2疫苗接种的动物具有100％（10/10）Cap抗体阳性和100％（10/10）Rep'抗体阳性。接种重组亚基PCV2疫苗的豚鼠的Cap抗体阳性率为100％（10/10），而Rep'抗体的豚鼠则没有（0/10）。Rep'iELISA和PCV2抗体检测试剂盒（商业）的组合检测结果表明，接种了全病毒灭活的PCV2疫苗或PCV2 SD / 2017的猪具有100％（5/5）Cap抗体阳性和100％（ 5/5）Rep'抗体阳性。接种重组亚基PCV2疫苗的猪的Cap抗体阳性率为100％（5/5），而Rep'抗体的猪则没有（0/10）。结论。本文介绍了一种有效的iELISA方法，该方法可将PCV2的自然感染（Cap和Rep阳性）或全病毒灭活疫苗（Cap和Rep阳性）与亚单位疫苗免疫（Cap阳性，Rep阴性）区分开。这些比较分析对于控制猪群中的PCV2可能非常有用。