Adsorption of a porcine reproductive and respiratory syndrome virus DNA vaccine candidate onto biodegradable nanoparticles improves immunogenicity in mice.

Porcine reproductive and respiratory syndrome (PRRS) is an economically devastating viral disease of pigs. Safer and more effective vaccines are urgently needed. In this study, a synthetic ORF5 gene of porcine reproductive and respiratory syndrome virus (PRRSV) was adsorbed onto poly(D, L-lactide-co-glycolide)/polyethylenimine (PLGA/PEI) nanoparticles. We prepared a PLGA-nanoparticle-adsorbed PRRSV DNA vaccine and a PEI-DNA complex. The results showed that these model vaccines could significantly enhance humoral and cellular immune responses when compared with the responses induced by pcDNA3.1-SynORF5, a plasmid construct for expression of PRRSV ORF5. PLGA-branched PEI nanoparticles induced the most efficient immune response. The delivery system and adjuvant provide new models for the development of vaccines against PRRSV.