In Silico Design, Optimization, and Evaluation of a Multi-Epitope Vaccine Targeting the Collagen Adhesin Protein.

Necrotic enteritis (NE), caused by pathogenic , poses a significant threat to global poultry health, with estimated annual losses exceeding USD 6 billion. The rising incidence of NE has been associated with the reduced use of antibiotic growth promoters, underscoring the urgent need for alternative control measures such as vaccination. Collagen adhesin protein (CNA), a key virulence factor in NE pathogenesis, represents a promising vaccine target. The US Food and Drug Administration has begun phasing out animal testing requirements for biologics and monoclonal antibody drugs. In this study, a computational multi-epitope vaccine (MEV) targeting CNA was designed by integrating predicted Cluster of Differentiation (CD)4 helper T lymphocyte (Th), CD8 cytotoxic T lymphocyte (CTL), and B-cell epitopes. Bioinformatics tools were used to identify immunogenic, antigenic, and non-allergenic epitopes assembled into a 115-amino-acid peptide vaccine construct. The candidate demonstrated strong stability and solubility. In silico immune simulation predicted robust immune responses, including elevated IgG and IgM antibody levels, plasma cell proliferation, Th memory formation, and CTL activation, comparable to responses elicited by a full-length CNA. These findings support the potential of the designed peptide as one of the multiple effective NE vaccine components, offering a promising alternative to antibiotic-based approaches in poultry disease management.