Reverse vaccinology and immunoinformatics-driven design of a multiepitope vaccine candidate against Renibacterium salmoninarum.

Abstract

Renibacterium salmoninarum, the etiological agent of bacterial kidney disease (BKD), remains a major challenge for salmonid aquaculture due to its intracellular lifestyle, chronic infection pattern, and the limited efficacy of current control strategies. In this study, a multiepitope vaccine candidate against Renibacterium salmoninarum was designed using reverse vaccinology and immunoinformatics approaches. Conserved antigenic proteins shared among three bacterial strains were identified through a systematic screening pipeline that included virulence prediction, essentiality analysis, antigenicity assessment, and exclusion of host homologs. Selected B-cell, MHC-I, and MHC-II epitopes were assembled into a chimeric construct and combined with conserved flagellin D0/D1 domains as a TLR5-targeting molecular adjuvant. The resulting construct, designated RS-MEVC, exhibited favorable predicted physicochemical and immunological properties, including high antigenicity, non-allergenicity, structural stability, and favorable stereochemical quality. Three-dimensional modeling revealed a predominantly α-helical structure, and structural validation supported the reliability of the refined model. Molecular docking predicted a stable interaction between RS-MEVC and Atlantic salmon TLR5, supported by multiple hydrogen bonds, salt bridges, and extensive intermolecular contacts. Molecular dynamics simulations further indicated stable conformational behavior of both the free vaccine construct and the vaccine-TLR5 complex, while MM-PBSA analysis predicted favorable binding energetics. Codon optimization and in silico cloning supported the feasibility of recombinant expression in Escherichia coli. Overall, these findings identify RS-MEVC as a promising computationally designed vaccine candidate against BKD and provide a rational framework for its subsequent experimental evaluation in salmonids.