Sheng Xiuzhen, Zhang Honghua, Liu Min, Tang Xiaoqian, Xing Jing, Chi Heng, Zhan Wenbin
Laboratory of Pathology and Immunology of Aquatic Animals, KLMME, Ocean University of China, Qingdao 266003, China.
Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China.
Vaccines (Basel). 2023 Mar 10;11(3):624. doi: 10.3390/vaccines11030624.
is a severe Gram-positive pathogen that can infect a wide range of freshwater and marine fish species. In continuation of our earlier studies on the development of vaccine candidates, pyruvate dehydrogenase E1 subunit alpha (PDHA1) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were highly efficacious in protecting flounder () against . In the present study, to investigate the potential of multi-epitope vaccination strategy to prevent flounder against infection, the liner B-cell epitopes of PDHA1 and GAPDH proteins were predicted using a bioinformatics approach and were identified by immunoassay, and recombinant B-cell multi-epitopes of PDHA1 and GAPDH (rMEPIP and rMEPIG) containing immunodominant epitope-concentrated domains were expressed in BL21 (DE3) and were used as a subunit vaccine to immunize healthy flounder, while recombinant PDHA1 (rPDHA1), GAPDH (rGAPDH) and formalin-inactivated (FKC) served as controls. Then, the immunoprotection efficacy of rMEPIP and rMEPIG was evaluated by determining the percentages of CD4-1, CD4-2, CD8β T lymphocytes and surface-IgM-positive (sIgM) lymphocytes in peripheral blood leucocytes (PBLs), spleen leucocytes (SPLs) and head kidney leucocytes (HKLs), as well as total IgM, specific IgM, and relative percentage survival (RPS) post immunization, respectively. It was found that fish immunized with rPDHA1, rGAPDH, rMEPIP, rMEPIG and FKC showed significant increases in sIgM, CD4-1, CD4-2, and CD8β lymphocytes and production of total IgM and specific IgM against or recombinant proteins rPDHA1 and rGAPDH, which indicated the activation of humoral and cellular immune responses after vaccination. Moreover, RPS rate of the multi-epitope vaccine rMEPIP and rMEPIG groups reached 74.07% and 77.78%, higher than that of rPDHA1 and rGAPDH (62.96% and 66.67%) and KFC (48.15%). These results demonstrated that B-cell multi-epitope protein vaccination, rMEPIP and rMEPIG, could give a better protective effect against infection, which provided a promising strategy to design the efficient vaccine in teleost fish.
是一种严重的革兰氏阳性病原体，可感染多种淡水和海水鱼类。在我们早期关于候选疫苗开发的研究基础上，丙酮酸脱氢酶E1亚基α（PDHA1）和甘油醛-3-磷酸脱氢酶（GAPDH）在保护牙鲆（）免受感染方面具有高效性。在本研究中，为了探究多表位疫苗接种策略预防牙鲆感染的潜力，采用生物信息学方法预测了PDHA1和GAPDH蛋白的线性B细胞表位，并通过免疫测定进行鉴定，含有免疫显性表位集中结构域的PDHA1和GAPDH重组B细胞多表位（rMEPIP和rMEPIG）在BL21（DE3）中表达，并用作亚单位疫苗免疫健康牙鲆，而重组PDHA1（rPDHA1）、GAPDH（rGAPDH）和福尔马林灭活（FKC）作为对照。然后，通过测定外周血白细胞（PBL）、脾白细胞（SPL）和头肾白细胞（HKL）中CD4-1、CD4-2、CD8β T淋巴细胞和表面IgM阳性（sIgM）淋巴细胞的百分比，以及免疫后总IgM、特异性IgM和相对存活率（RPS），评估rMEPIP和rMEPIG的免疫保护效果。结果发现，用rPDHA1、rGAPDH、rMEPIP、rMEPIG和FKC免疫的鱼，其sIgM、CD4-1、CD4-2和CD8β淋巴细胞显著增加，并且产生了针对或重组蛋白rPDHA1和rGAPDH的总IgM和特异性IgM，这表明疫苗接种后体液免疫和细胞免疫反应被激活。此外，多表位疫苗rMEPIP和rMEPIG组的RPS率分别达到74.07%和77.78%，高于rPDHA1和rGAPDH组（62.96%和66.67%）以及KFC组（48.15%）。这些结果表明，B细胞多表位蛋白疫苗接种，即rMEPIP和rMEPIG，能够对感染提供更好的保护作用，这为设计硬骨鱼高效疫苗提供了一种有前景的策略。
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