Protective efficacy of PLGA microspheres loaded with divalent DNA vaccine encoding the ompA gene of Aeromonas veronii and the hly gene of Aeromonas hydrophila in mice

•We constructed the recombinant plasmid pET-28a-ompA-hly and studied its immunogenicity.•We used PLGA as a carrier and prepared the ompA-hly antigen-loaded PLGA microspheres.•The protection rate of ompA-hly antigen-loaded PLGA microspheres vaccine is 100%.•The ompA-hly antigen-loaded PLGA microspheres vaccine provides a long-time protection.