In-silico design and evaluation of a multi-epitope vaccine candidate against PRRSV1(Lelystad European strain) using immunoinformatics approaches

Porcine reproductive and respiratory syndrome virus type 1 (PRRSV-1), also known as the European genotype, remains a major threat to the global swine industry because of its high antigenic variability and limited cross-protective immunity This study used a combination of immunoinformatics and structural vaccinology approach to design and prioritize multi-epitope vaccines against PRRSV-1. B-cell epitopes, cytotoxic T lymphocyte (CTL) epitopes, and helper T lymphocyte (HTL) epitopes were predicted from key structural proteins, namely, GP2a, GP4, GP5, M and N. The epitopes were further prioritized based on predicted antigenicity, non-allergenicity, non-toxicity, and their capacity to induce IFN-γ and IL-4 responses. The two best multi-epitope vaccine constructs, PRRSV-Vax-1 and PRRSV-Vax-2, were designed by linking selected epitopes with suitable linkers and adjuvants, β-defensin and HBHA, respectively. Physicochemical properties of both the vaccine constructs predicted them to be stable, soluble and ideal for expression. Three-dimensional structures predicted by AlphaFold3 indicated reasonable models as per PROCHECK and ProSA-web analysis. Docking with TLR4 receptor was predicted to have good vaccine-receptor interactions, and 100-ns molecular dynamics (MD) simulation showed docked complexes were stable. In-silico Immune simulation (C-ImmSim) indicated possible humoral and cellular immune responses, such as antibody concentrations, cytokine secretion and immune memory cell formation. In-silico codon optimization also showed acceptable codon adaptation index values and GC content for potential expression in Escherichia coli with pET28a (+) vectors. Overall, PRRSV vaccine showed positive in-silico immunogenicity and stability and were selected as potential vaccine constructs for future experimental validation against PRRSV-1.