isopropyl-thiogalactoside and Gram-Negative-Bacterial-Infections

The transcription factor JunB can induce physiological or pathological responses to various stimuli, including immune stimulants and bacteria, and plays an important role in the immune response process. In this study, we identified a JunB family member in Schizothorax prenanti (S. prenanti), which was designated SpJunB. The complete coding sequence (CDS) of SpJunB was 930 bp in length, which was submitted to GenBank (ID: MN215886). SpJunB encodes a putative protein of 309 amino acids, which is highly homologous to JunB of common carp. The SpJunB protein contained a conserved JunB domain, and its 3D structure was also highly similar to (77.61%) the human SpJunB protein. SpJunB was found to be extensively expressed in various tissues, with the highest expression in the spleen. The expression of SpJunB was significantly upregulated after Aeromonas hydrophila (A. hydrophila) challenge. Prokaryotic expression indicated that a 51 kDa recombinant protein was obtained after induction with 1.5 mmol/L isopropyl-beta-D-thiogalactopyranoside (IPTG) for 6 h at 37 °C. The expression levels of IL-1β, IL-6 and IL-8 were significantly upregulated (p < 0.01) after treatment of S. prenanti with the SpJunB protein. The activities of SOD, AKP and LZM were also significantly increased (p < 0.01) after the treatment of S. prenanti with the SpJunB protein. Simultaneously, the SpJunB protein reduced the infection rate of A. hydrophila in S. prenanti. In conclusion, SpJunB may improve the immune functions of S. prenanti. It will be beneficial to further study the immune mechanism of JunB in fish.

Topics: Aeromonas hydrophila; Animals; Cloning, Molecular; Cyprinidae; Fish Diseases; Fish Proteins; Gram-Negative Bacterial Infections; Humans; Immunity, Innate; Interleukin-1beta; Interleukin-6; Interleukin-8; Isopropyl Thiogalactoside; Phylogeny; Protein Domains; Transcription Factors

The use of a recombinant bacterial vector vaccine is an attractive vaccination strategy to induce an immune response to a carried protective antigen. The superiorities of live bacterial vectors include mimicry of a natural infection, intrinsic adjuvant properties, and the potential for administration by mucosal routes. Escherichia coli is a simple and efficient vector system for production of exogenous proteins. In addition, many strains are nonpathogenic and avirulent, making it a good candidate for use in recombinant vaccine design. In this study, we screened 23 different iron-regulated promoters in an E. coli BL21(DE3) vector and found one, P(viuB), with characteristics suitable for our use. We fused P(viuB) with lysis gene E, establishing an in vivo inducible lysis circuit. The resulting in vivo lysis circuit was introduced into a strain also carrying an IPTG (isopropyl-β-d-thiogalactopyranoside)-inducible P(T7)-controlled protein synthesis circuit, forming a novel E. coli-based protein delivery system. The recombinant E. coli produced a large amount of antigen in vitro and could deliver the antigen into zebrafish after vaccination via injection. The strain subsequently lysed in response to the iron-limiting signal in vivo, implementing antigen release and biological containment. The gapA gene, encoding the protective antigen GAPDH (glyceraldehyde-3-phosphate dehydrogenase) from the fish pathogen Aeromonas hydrophila LSA34, was introduced into the E. coli-based protein delivery system, and the resultant recombinant vector vaccine was evaluated in turbot (Scophtalmus maximus). Over 80% of the vaccinated fish survived challenge with A. hydrophila LSA34, suggesting that the E. coli-based antigen delivery system has great potential in bacterial vector vaccine applications.

Topics: Aeromonas hydrophila; Animals; Antigens, Bacterial; Bacterial Vaccines; Bacteriolysis; Escherichia coli; Escherichia coli Proteins; Flatfishes; Glyceraldehyde-3-Phosphate Dehydrogenases; Gram-Negative Bacterial Infections; Green Fluorescent Proteins; Iron; Isopropyl Thiogalactoside; Plasmids; Promoter Regions, Genetic; Signal Transduction; Vaccines, Synthetic; Zebrafish