Research Center for Swine Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
Sichuan Science-Observation Experimental Station for Veterinary Drugs and Veterinary Diagnostic Technology, Ministry of Agriculture, Chengdu 611130, China.
Int J Biol Macromol. 2023 Nov 1;251:126327. doi: 10.1016/j.ijbiomac.2023.126327. Epub 2023 Aug 12.
Porcine deltacoronavirus (PDCoV) is an emerging swine enteropathogenic coronavirus that mainly threatens newborn piglets and poses a potential broad cross-species transmission risk. The antigenic epitopes of PDCoV are currently unidentified, and no information about T cell epitopes is available. Here, T-cell epitopes of PDCoV structural proteins were predicted using computational methods. 17 epitope peptides were synthesized and then screened using ELIspot, intracellular cytokine staining (ICS), and RT-qPCR detection of IFN-γ mRNA to evaluate their ability to elicit interferon-gamma (IFN-γ) responses in peripheral blood mononuclear cells (PBMCs) from PDCoV-challenged pigs. Five peptides (M1, M2, M3, N6, and S4) elicited high levels of IFN-γ and were investigated further as potential T-cell epitope candidates. All five peptides were cytotoxic T lymphocyte (CTL) epitopes, and two peptides (M3, N6) were recognized simultaneously by CD8 + and CD4 + T cells. A multi-epitope peptide combining the five epitopes (designated "5T") was synthesized and its immune response and protection efficacy was evaluated in a piglet model. ELISpot assay results indicated that 5T induces robust epitope-specific cellular immune responses. Four epitopes (M1, M2, N6, S4) elicited IFN-γ responses in 5T-vaccinated piglets. No obvious protection efficacy was detected in piglets vaccinated with 5T alone. Our results provide valuable information concerning PDCoV-related antigenic epitopes and will be useful in the design of epitope-based vaccines.
猪德尔塔冠状病毒（PDCoV）是一种新兴的猪肠道致病性冠状病毒，主要威胁新生仔猪，具有广泛的潜在跨种传播风险。PDCoV 的抗原表位目前尚未确定，也没有关于 T 细胞表位的信息。本研究采用计算方法预测 PDCoV 结构蛋白的 T 细胞表位。合成了 17 个表位肽，然后通过 ELIspot、细胞内细胞因子染色（ICS）和 IFN-γ mRNA 的 RT-qPCR 检测评估其在 PDCoV 攻毒猪外周血单个核细胞（PBMC）中诱导干扰素-γ（IFN-γ）反应的能力。5 个肽（M1、M2、M3、N6 和 S4）诱导高水平的 IFN-γ，并进一步作为潜在的 T 细胞表位候选物进行研究。这 5 个肽均为细胞毒性 T 淋巴细胞（CTL）表位，其中 2 个肽（M3、N6）同时被 CD8+和 CD4+T 细胞识别。合成了一个包含这 5 个表位的多表位肽（命名为“5T”），并在仔猪模型中评估了其免疫反应和保护效果。ELISpot 检测结果表明，5T 诱导了强烈的表位特异性细胞免疫反应。5T 疫苗接种仔猪中，4 个表位（M1、M2、N6、S4）可诱导 IFN-γ 应答。单独接种 5T 的仔猪未检测到明显的保护效果。本研究提供了与 PDCoV 相关的抗原表位的有价值信息，将有助于基于表位的疫苗的设计。
