Multi-Epitope Vaccine Designed In-Silico Based on the Conserved Fragments in Viral Proteins for Broad-Spectrum Protection to Porcine Reproductive and Respiratory Syndrome Virus

Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) is a major viral threat to swine, causing significant economic loss in global pig farming industry. The virus exists in two major genotypes, both characterized by high mutation rates and genetic variability, complicating the development of a universally effective vaccine and the control of disease consequently. To address this challenge, a novel multi-epitope-based vaccine was designed to elicit a robust and cross-protective immune response against multiple PRRSV strains. The complete sequences of PRRSV encoded proteins were retrieved worldwide, and the conserved fragments were identified through alignment of polypeptide sequences. Subsequent screening was conducted screened epitopes for their potential to be safe and to activate B cells, CTLs and HTLs. By conjugating the selected epitopes with distinct adjuvant proteins, three vaccine candidates were constructed and termed as PRRSV-Vaccine (PRRSV-V-1, PRRSV-V-2, and PRRSV-V-3 respectively). Furthermore, systematic evaluations of their physiochemistry properties, structural stability, binding with pattern recognition receptors and induction of host immune system were performed. PRRSV-V-2 was demonstrated with most promising physicochemical and structural characteristics, strong binding with TLR3 and TLR8, and most vigorous reactions of host immune response. As the most promising candidate, the recombinant PRRSV plasmid was in-silico designed for expression in Escherichia coli. Our study proposed a novel approach to PRRSV vaccine development against PRRSV, offering a promising strategy for controlling the infection across diverse PRRSV virus strains in swine.