Evaluation of immunological effects of two DNA vaccines against Nocardia seriolae in hybrid snakehead

Yiming Wen; Guoquan Chen; Yuhao Li; Deyu Ning; Wanna Sirimanapong; Liqun Xia

doi:10.1016/j.fsi.2025.110233

Evaluation of immunological effects of two DNA vaccines against Nocardia seriolae in hybrid snakehead

Fish Shellfish Immunol. 2025 Mar 7:161:110233. doi: 10.1016/j.fsi.2025.110233. Online ahead of print.

Authors

Yiming Wen¹, Guoquan Chen¹, Yuhao Li¹, Deyu Ning¹, Wanna Sirimanapong², Liqun Xia³

Affiliations

¹ Shenzhen Institute of Guangdong Ocean University, Fisheries College of Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy Culture, Guangdong, China; Guangdong Provincial Engineering Research Center for Aquatic Animal Health Assessment, Shenzhen Public Service Platform for Evaluation of Marine Economic Animal Seedings, Guangdong, China.
² Veterinary Aquatic Animal Research & Health Care Unit, Department of Clinical Sciences and Public Health, Faculty of Veterinary Science, Mahidol University, Nakhon-pathom, Thailand.
³ Shenzhen Institute of Guangdong Ocean University, Fisheries College of Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy Culture, Guangdong, China; Guangdong Provincial Engineering Research Center for Aquatic Animal Health Assessment, Shenzhen Public Service Platform for Evaluation of Marine Economic Animal Seedings, Guangdong, China. Electronic address: xialq@gdou.edu.cn.

PMID: 40058678
DOI: 10.1016/j.fsi.2025.110233

Abstract

Although DNA vaccines hold significant potential, their practical application in aquaculture remains limited. In both mammals and teleost fish, B cells, which recognize antigens and produce antibodies, play an important role in immunity. In this study, B-cell epitopes capable of inducing fish immunity from IS701 family transposase (IS701) and molybdopterin-dependent oxidoreductase (Mol) proteins of Nocardia seriolae were screened. PcDNA-IS701 and pcDNA-Mol recombinant plasmids were constructed. The results showed that two proteins possessed multiple B-cell epitopes, and both pcDNA-IS701 and pcDNA-Mol induced innate immunity and specific antibody responses, along with increased mRNA expression levels of genes encoding humoral (MHCIIα and CD4) and cell-mediated (MHCIα and CD8α) immunity. In addition, both pcDNA-IS701 and pcDNA-Mol strengthened the protection against N. seriolae infection, with immune protection rates of 45.06 % for IS701 and 61.04 % for Mol, respectively. In conclusion, pcDNA-IS701 and pcDNA-Mol are candidate DNA vaccines for nocardiosis in fish.

Keywords: B-cell epitopes; DNA vaccines; Immune response; N. seriolae.