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-γ (IFN-γ), 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-γ 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.

To explore the immunoregulatory function of peony seed proteolysis product in mice, the protein from peony seed meal was extracted and hydrolyzed with bromelain. The peony seed proteolysis product was fed to mice at three different doses of 0.25, 0.5, and 1.0 g/kg for 21 days. The immunoregulation abilities of peony seed proteolysis product after each of these doses were evaluated in mice. Our results showed that all immune indices were higher in mice that had received a lavage with peony seed proteolysis product than in control mice. The immune indices of immune organs, delayed‐type hypersensitivity reaction (DTH), phagocytosis of peritoneal macrophages, serum hemolysin levels, lymphocyte proliferation (SI value), and levels of IFN‐γ and IL‐4 in the middle dose and high dose groups were significantly higher (p < .05) or extremely significant (p < .01) in comparison with the control group. These results indicate that the peony seed proteolysis product enhances immunological functions in mice. Practical applications Peony seed is rich in proteins and can be extracted and hydrolyzed using bromelain. The peony seed proteolysis product can enhance the nonspecific, humoral, and cellular immune responses. Thus, peony seed could be of potential value to obtain peony seed protein, which can be further developed and utilized in the manufacture of functional health products.

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