Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Key Laboratory of Veterinary Biological Engineering and Technology, Ministry of Agriculture; Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing, China.
Jiangsu Coinnovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, People's Republic of China.
Microbiol Spectr. 2023 Jun 15;11(3):e0523322. doi: 10.1128/spectrum.05233-22. Epub 2023 Apr 6.
Porcine epidemic diarrhea (PED) is a highly contagious intestinal infectious disease caused by porcine epidemic diarrhea virus (PEDV). Large-scale outbreaks of PEDV have caused huge economic losses to the pig industry since 2010. Neutralizing antibodies play a pivotal role in protecting piglets from enteric infections. However, there has been no systematic report on the correlations between neutralizing antibody titers (NTs) and absorbance values of IgG or IgA to all PEDV individual structural proteins in clinical serum, fecal, and colostrum samples. In this study, the spike protein S1 domain (S1), membrane protein (M), envelope protein (E), and nucleocapsid protein (N) of the variant PEDV strain AH2012/12 were expressed and purified by using the human embryonic kidney (HEK) 293F expression system. A total of 92 clinical serum samples, 46 fecal samples, and 33 colostrum samples were collected, and the correlations between IgG or IgA absorbance values and NTs were analyzed. values revealed that anti-S1 IgA absorbance values show the highest agreement with NTs in all serum, fecal, and colostrum samples, followed by the N protein. The correlations between anti-E or M IgA and NTs were very low. However, in the colostrum samples, both IgG and IgA to S1 showed high correlations with NTs. In addition, compared with E and M, the highest correlations of IgA absorbance values were with N and S1 in serum and fecal samples. Overall, this study revealed the highest correlation between NTs and IgA to PEDV S1 protein. Therefore, the diagnostic method with anti-S1 IgA can be used as a powerful tool for assessing the immune status of pigs. The humoral immune response plays an important role in virus neutralization. Against PEDV, both IgG and the mucosal immune component IgA play roles in virus neutralization. However, which plays a more prominent role and whether there are differences in different tissue samples are not clearly reported. Additionally, the relationship between IgG and IgA against individual structural proteins and viral neutralization remains unclear. In this study, we systematically determined the relationship between IgG and IgA against all PEDV structural proteins and viral neutralization in different clinical samples and found the highest correlation between neutralization activity and IgA to PEDV S1 protein. Our data have important guiding implications in the evaluation of immune protection.
猪流行性腹泻（PED）是一种由猪流行性腹泻病毒（PEDV）引起的高度传染性肠道传染病。自 2010 年以来，PEDV 的大规模爆发给养猪业造成了巨大的经济损失。中和抗体在保护仔猪免受肠道感染方面发挥着关键作用。然而，目前还没有系统地报道临床血清、粪便和初乳样本中针对所有 PEDV 个体结构蛋白的中和抗体滴度（NTs）与 IgG 或 IgA 吸光度值之间的相关性。在这项研究中，使用人胚肾（HEK）293F 表达系统表达和纯化了变异 PEDV 株 AH2012/12 的刺突蛋白 S1 结构域（S1）、膜蛋白（M）、包膜蛋白（E）和核衣壳蛋白（N）。共收集了 92 份临床血清样本、46 份粪便样本和 33 份初乳样本，并分析了 IgG 或 IgA 吸光度值与 NTs 的相关性。结果表明，在所有血清、粪便和初乳样本中，抗 S1 IgA 吸光度值与 NTs 的一致性最高，其次是 N 蛋白。抗 E 或 M IgA 与 NTs 的相关性非常低。然而，在初乳样本中，S1 的 IgG 和 IgA 均与 NTs 呈高度相关性。此外，与 E 和 M 相比，血清和粪便样本中 IgA 吸光度值与 N 和 S1 的相关性最高。总的来说，这项研究揭示了 NTs 与 PEDV S1 蛋白之间的最高相关性。因此，针对 S1 IgA 的诊断方法可以作为评估猪免疫状态的有力工具。体液免疫反应在病毒中和中起重要作用。针对 PEDV，IgG 和黏膜免疫成分 IgA 均在病毒中和中发挥作用。然而，哪种作用更为突出，以及在不同组织样本中是否存在差异，目前尚不清楚。此外，针对个体结构蛋白的 IgG 和 IgA 与病毒中和之间的关系尚不清楚。在这项研究中，我们系统地确定了不同临床样本中针对所有 PEDV 结构蛋白的 IgG 和 IgA 与病毒中和之间的关系，发现中和活性与 PEDV S1 蛋白的 IgA 之间具有最高的相关性。我们的数据对免疫保护的评估具有重要的指导意义。
