DNA vaccines have been widely employed in controlling viral and bacterial infections in mammals and teleost fish.Co-injection of molecular Color Book adjuvants, including chemokines, cytokines, and immune co-stimulatory molecules, is one of the potential strategies used to improve DNA vaccine efficacy.In mammals and teleost fish, interleukin-34 (IL-34) had been described as a multifunctional cytokine and its immunological role had been confirmed; however, the adjuvant capacity of IL-34 remains to be elucidated.In this study, IL-34 was identified in largemouth bass.A recombinant plasmid of IL-34 (pcIL-34) was constructed and co-administered with a DNA vaccine encoding hypoxic response protein 1 (Hrp1; pcHrp1) to evaluate the adjuvant capacity of pcIL-34 against Nocardia seriolae infection.
Our results indicated that pcIL-34 co-injected with pcHrp1 not only triggered innate immunity and a specific antibody response, but also enhanced the mRNA expression level of immune-related genes encoding for cytokines, chemokines, and humoral and cell-mediated immunity.Moreover, pcIL-34 enhanced the protection of pcHrp1 against N.seriolae challenge and conferred the relative percent survival MOISTURIZING SHAMPOO of 82.14%.Collectively, IL-34 is a promising adjuvant in a DNA vaccine against nocardiosis in fish.