Identification of candidate antigens for a vaccine against Avibacterium paragallinarum using reverse vaccinology.

Infectious coryza, caused by Avibacterium paragallinarum, is a respiratory disease that results in significant economic losses for the global poultry industry. Current inactivated whole-cell vaccines often fail to provide broad protection, largely due to the extensive antigenic diversity among circulating strains. To address this limitation, we applied a reverse vaccinology strategy to identify candidate antigens for rational subunit vaccine development. Using genomic and proteomic data from 95 Av. paragallinarum strains and a subtractive genomics-immunoinformatics pipeline, we prioritized proteins predicted to be non-similar to host proteins, antigenic, surface-exposed, and conserved across strains. A curated dataset of experimentally validated bacterial antigens was incorporated as a benchmark to assess the predictive performance of the pipeline. Thirteen proteins fulfilled all selection criteria and were further characterized based on structural features, physicochemical properties, virulence association, and essentiality. Notably, homologs of ten candidates have previously conferred protective immunity in experimental subunit vaccines against other Gram-negative bacteria across diverse animal models. These findings provide a rationally prioritized set of conserved candidate antigens and a framework to guide the development of next-generation subunit vaccines against infectious coryza.