Rationally designed self-assembled peptide nanofibers provoke robust humoral immunity against nervous necrosis virus

Nervous necrosis virus (NNV) poses devastating mortality risks to almost all marine fish, causing significant economic losses to the marine fish aquaculture industry, particularly in juvenile groupers. However, no effective NNV vaccine is available. To counter this, we report a smart strategy of a rationally designed modular peptide vaccine platform (CP^64-83-Q11) that recapitulates the antigen peptide CP^64-83 and a Q11 self-assembling domain. An anti-NNV phage antibody library was constructed and used for screening anti-NNV antibody. Bioinformatics and surface-plasmon resonance were utilized to identify the antigen epitope of NNV. Furthermore, the CP^64-83-Q11 nanofiber was designed and constructed. The cellular and tissular uptake of CP^64-83-Q11 was analyzed in vitro and in vivo. Moreover, the immunogenicity and the protective efficacy of the CP^64-83-Q11 nanofibers were evaluated by determining the expression of antigen-presenting indicators, antibody levels, and response to viral challenge to vaccinated fish. It has been proven that CP^64-83-Q11 nanofiber could efficiently deliver antigen peptide to immune tissues and induce robust humoral immunity against NNV infection, which provided a protection rate of approximately 88%. This study provides an effective strategy for aquatic vaccine design, which will be beneficial for the application and development of vaccines in the aquaculture industry.IMPORTANCEViral diseases have constantly caused a great threat to global public health, resulting in an urgent need for effective vaccines. However, the current viral vaccines are often showing low immunogenicity. NNV, a serious threat to almost marine fish, was used as a viral model in this study. To address the threat of NNV, an anti-NNV antibody phage library was constructed and used for anti-NNV antibody biopanning. Based on bioinformatics and surface-plasmon resonance, we validated an antigen peptide for NNV (CP^64-83) with high-affinity binding ability to the anti-NNV antibody. Moreover, a modular peptide vaccine delivery platform (CP^64-83-Q11) was rationally designed using phage display technology and bioinformatics. CP^64-83-Q11 could efficiently deliver into immune tissues and provide effective protection against NNV infection by inducing a significant level of humoral immunity. This study offers new insights into rational viral vaccine design for fish, which could provide methods for the prevention and treatment of animal viral diseases.