Interleukin 34 Serves as a Novel Molecular Adjuvant against Nocardia Seriolae Infection in Largemouth Bass (Micropterus Salmoides)

Abstract

DNA vaccines have been widely employed in controlling viral and bacterial infections in mammals and teleost fish. Co-injection of molecular 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 of 82.14%. Collectively, IL-34 is a promising adjuvant in a DNA vaccine against nocardiosis in fish.

The twin cytokines interleukin-34 and CSF-1: masterful conductors of macrophage homeostasis

“…Moreover, overexpression of IL-34 showed tissue-dependent expression of pro- and anti-inflammatory mediators via JAK/STAT signaling pathways, depending on the manner that was associated with infection resolution 70 . In this context, IL-34 could be used as an adjuvant to DNA vaccine treatment against nocardiosis infection in fish 71 . Finally, zebrafish have been suggested as a good model for studying the role of IL-34 during brain development or in brain disorders and liver or skin diseases 72 , 73 , 74 .…”

Gill Junction Injury and Microbial Disorders Induced by Microcystin-Leucine Arginine in Lithobates catesbeianus Tadpoles

“…The gill mucosa is an important immune barrier, including innate and adaptive immunity [ 46 , 47 ]. Lysozyme is the widely distributed enzyme of the innate immune system that exhibits antibacterial activity [ 48 ]. After MC-LR exposure, the expression of lysozyme was reduced in gill tissue, while other nonspecific and specific immunities were upregulated.…”

Screening and evaluating honokiol from Magnolia officinalis against Nocardia seriolae infection in largemouth bass (Micropterus Salmoides)

“…It is a chronic disease that usually lacks observable signs in fish during the early infection, but outbreak occurs in the mid‐phase of the culture cycle, at which point it is difficult to cure and thus resulting in severe economic losses to breeders (Elkesh et al, 2013; (Wang et al, 2007); Wang et al, 2009). The causative agent of nocardiosis is the gram‐positive, aerobic, filamentous bacterium Nocardia spp., of which Nocardia seriolae is the most frequent species (Hoang et al, 2020; Lei et al, 2020). Since the first case of N. seriolae infection reported in seabass in 2000, more than 20 freshwater and marine fish species have been found to be susceptible to this pathogen (Chen et al, 2000; Huang et al, 2021).…”

“…At present, N. seriolae has become a primary pathogenic bacterium in aquaculture, posing an increasing threat to aquaculture industry, especially in Asia (Huang et al, 2021; Lei et al, 2020; Wang et al, 2009). Current therapeutic means rely mainly on a limited number of antibiotics; however, prolonged and extensive administration may trigger a series of serious problems, such as environmental contamination, drug residues and a rise in drug resistance (Hoang et al, 2020; Maekawa et al, 2018). Therefore, there is an immediate need to develop new prophylactic or therapeutic agents against nocardiosis in aquaculture.…”

“…Since its introduction to China in the 1980s, the production has been continuously increasing and has become a commercially important cultured fish in China (Huang et al, 2021). However, nocardiosis caused by N. seriolae poses a great threat to the largemouth bass aquaculture industry (Hoang et al, 2020; Huang et al, 2021; Lei et al, 2020). In this study, 80 medicinal plants were selected as candidates, and the antibacterial activity of their crude extracts was evaluated using a modified microplate resazurin assay method.…”