School of Life Science, Jilin Normal University, Siping 136000, China.
Hebei Veterinary Biotechnology Innovation Center, College of Veterinary Medicine, Hebei Agricultural University, Baoding 071000, China.
Vet Microbiol. 2020 Jul;246:108742. doi: 10.1016/j.vetmic.2020.108742. Epub 2020 May 31.
Porcine epidemic diarrhea virus (PEDV) causes severe clinical diarrhea in neonatal piglets, with reported mortality rates between 70-100%. The humoral immunity, especially the local intestinal IgA responses, plays an important role in the immune protection against PEDV infection. In this study, we evaluated the isotype antibody responses against the PEDV nucleocapsid (N) protein and the spike (S) protein subunits 1 (S1) and 2 (S2) in the serum and intestine of piglets. We also determined its serum neutralizing activity against the PEDV field strain HBMC2012 in 21-day-old piglets. Enzyme-linked immunosorbent assays (ELISA) revealed that the production of IgM against the N protein and S1 subunit was higher compared to the S2 subunit. The anti-S2 IgA antibodies were higher than the anti-N protein and anti-S1 IgA at 3 days post-infection (dpi). The specific IgA responses to the S2 subunit were higher than the responses observed in S1. The specific IgG responses against S1 and S2 subunits exceeded those of N protein. The serum neutralizing activities against PEDV were relatively low with a tendency to decline over time. No isotype-specific antibodies were found in the intestinal contents from infected pigs, except the one with weak IgA responses against N protein at 28 dpi. Immunohistochemical staining showed that a few IgM, IgA, and IgG antibody-secreting cells were mainly located in the mucosa of the duodenum and ileum of PEDV-infected pigs at 3 dpi. This study suggests poor systemic and intestinal isotype-specific antibody responses, especially those of IgA, and weak serum neutralizing activities against the field PEDV strain in piglets.
猪流行性腹泻病毒（PEDV）可引起仔猪严重的临床腹泻，其死亡率在 70-100%之间。体液免疫，尤其是局部肠道 IgA 应答，在抵抗 PEDV 感染的免疫保护中发挥着重要作用。在本研究中，我们评估了血清和肠道中针对 PEDV 核衣壳（N）蛋白和刺突（S）蛋白亚单位 1（S1）和 2（S2）的同型抗体应答。我们还测定了针对 PEDV 田间分离株 HBMC2012 的血清中和活性。酶联免疫吸附试验（ELISA）显示，针对 N 蛋白和 S1 亚单位的 IgM 产生高于 S2 亚单位。与感染后 3 天相比，针对 S2 亚单位的抗-S2 IgA 抗体高于抗-N 蛋白和抗-S1 IgA 抗体。针对 S2 亚单位的特异性 IgA 应答高于 S1 观察到的应答。针对 S1 和 S2 亚单位的特异性 IgG 应答高于 N 蛋白。针对 PEDV 的血清中和活性相对较低，且随时间推移呈下降趋势。除了在 28 天感染后观察到针对 N 蛋白的微弱 IgA 应答外，在感染猪的肠内容物中未发现任何同型特异性抗体。免疫组织化学染色显示，在 PEDV 感染猪的十二指肠和空肠黏膜中，少量 IgM、IgA 和 IgG 抗体分泌细胞主要位于黏膜中。该研究表明，仔猪存在较差的系统和肠道同型特异性抗体应答，尤其是 IgA 应答，以及针对田间 PEDV 株的弱血清中和活性。
