Immune efficacy of DNA vaccines based on oprL and oprF genes of Pseudomonas aeruginosa in chickens

Pseudomonas aeruginosa (P. aeruginosa) is a zoonotic pathogen that can infect a variety of animals, including poultry. However, as there is no commercial vaccine available it is imperative that new and effective vaccines are developed. In this study, 2 monovalent DNA vaccines (pOPRL and pOPRF), one divalent combination DNA vaccine (pOPRL+pOPRF) and one fusion DNA vaccine (pOPRLF) were constructed based on the oprL and oprF genes of P. aeruginosa. These vaccines were administered to chickens, an outer membrane protein vaccine (OMP vaccine) and inactivated vaccine used as positive controls. The serum antibody, interferon-gamma (IFN-gamma), interleukin-2 (IL-2) and interleukin-4 (IL-4) concentrations were determined and lymphocyte proliferation assays were performed. After challenging with virulent P. aeruginosa, protective efficacy was evaluated. Following vaccination, serum antibodies, stimulation index (SI) values, concentrations of IL-2 and IFN-gamma in chickens vaccinated with the bivalent combination DNA vaccine and fusion DNA vaccine were found to be significantly higher than in those chickens vaccinated with the 2 monovalent DNA vaccines. Moreover, the immune indexes in the bivalent combination DNA vaccine group were higher than those in the fusion DNA vaccine group. However, the concentrations of IL-4 in the 4 DNA vaccine groups were of no significant difference. The protective efficacy rate provided by pOPRL, pOPRF, pOPRLF, pOPRL+pOPRF, inactivated vaccine and OMP vaccine were 53.3%, 40%, 66.7%, 80%, 93.3%, and 80%, respectively. The results indicate that DNA vaccines constructed with the oprL and oprF genes of P. aeruginosa, particularly the divalent combination DNA vaccine, represent better potential vaccines. This study has laid a foundation for the design and application of future DNA vaccines of P. aeruginosa.