OBJECTIVETo clone and secretion express cholera toxin B subunit (CTB) in food-grading Lactococcus lactis expression systems.

METHODSctB fragment that encoding CTB was amplified by polymerase chain reaction (PCR) using the genomic DNA of Vibrio cholera strain 569B as template and was inserted into two secretion expression vector pSQZ and pSQ to construct food-grading expression system L.lactis MBP71/pSQZ-ctB and L.lactis MBP71/pSQ-ctB. The expressed CTB was detected by Western-blot assay.

RESULTSThe ctB fragment was successfully amplified from Vibrio cholera strain 569B and inserted into two secretion expression vectors pSQZ and pSQ to construct food-grading expression system L. lactis MBP71/pSQZ-ctB and L. lactis MBP71/pSQ-ctB. Western-blot assay demonstrated that CTB was secretion and expressed from L.lactis MBP71 harboring vectors pSQZ-ctB and pSQ-ctB, and the quantity of CTB secreted by L. lactis MBP71/pSQ-ctB was about 2 microg/ml, higher than that of L. lactis MBP71/pSQZ-ctB.

CONCLUSIONCTB was successfully secreted and expressed by food-grading L. lactis expression systems.

Cholera Toxin ; biosynthesis ; secretion ; Food Microbiology ; Gene Expression ; Genetic Vectors ; Lactococcus lactis ; metabolism

A fusion gene CTB-PROIN, in which Proinsulin gene was fused to the 3' end of CTB gene by a hinge peptide 'GPGP', was constructed and cloned into pET-30a(+) to obtain a prokaryotic expression vector pETCPI. Subsequently the recombinant plasmid pETCPI was transformed into E. coli stain BL21 (DE3). After induced by IPTG, the expression product was analyzed by sodium dodecyl sulphate-polyacrylamide gel (15%) electrophoresis (SDS-PAGE), and its result indicated that the recombinant protein CTB-PROIN was expressed and accumulated as inclusion bodies. The recombinant CTB-PROIN protein accumulated to the level of 25% of total bacterial proteins. After inclusion bodies was denaturalized and refolded in vitro, significant assembly of monomers had occurred, and the recombinant protein represented assembled pentamers. The results of western blotting analysis also demonstrated that the fusion protein could be recognized by the anti-CT and anti-insulin antibody, respectively. In addition, the result of the CTB-PROIN-GM1 binding assay, that the protein could bind to monosialoganglioside specifically, showed it possesed biological activity in vitro. These results provided the possibility of developing a cheaper and more efficient oral vaccine for type I diabetes using such constructs.
Artificial Gene Fusion ; Cholera Toxin ; genetics ; Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; G(M1) Ganglioside ; metabolism ; Proinsulin ; genetics ; Recombinant Proteins ; biosynthesis ; genetics

Chloroplast-based expression system is promising for the hyper-expression of plant-derived recombinant therapeutic proteins and vaccines. To verify the feasibility of obtaining high-level expression of the SARS subunit vaccine and to provide a suitable plant-derived vaccine production platform against the severe acute respiratory syndrome coronavirus (SARS-CoV), a 193-amino acid fragment of SARS CoV spike protein receptor-binding domain (RBD), fused with the peptide vector cholera toxin B subunit (CTB), was expressed in tobacco chloroplasts. Codon-optimized CTB-RBD sequence was integrated into the chloroplast genome and homoplasmy was obtained, as confirmed by PCR and Southern blot analysis. Western blot showed expression of the recombinant fusion protein mostly in soluble monomeric form. Quantification of the recombinant fusion protein CTB-RBD was conducted by ELISA analysis from the transplastomic leaves at different developmental stages, attachment positions and time points in a day and the different expression levels of the CTB-RBD were observed with the highest expression of 10.2% total soluble protein obtained from mature transplastomic leaves. Taken together, our results demonstrate the feasibility of highly expressing SARS subunit vaccine RBD, indicating its potential in subsequent development of a plant-derived recombinant subunit vaccine and reagents production for antibody detection in SARS serological tests.
Chloroplasts ; metabolism ; Cholera Toxin ; Protein Interaction Domains and Motifs ; Recombinant Fusion Proteins ; biosynthesis ; SARS Virus ; Spike Glycoprotein, Coronavirus ; biosynthesis ; Tobacco ; metabolism ; Vaccines, Subunit ; biosynthesis

BACKGROUNDCholera toxin B subunit (CTB) was shown to be a potent adjuvant for protein immunogen, especially when inoculated through mucosal route. We aimed to optimize the expression approach for CTB and thereafter to determine the adjuvant effect on DNA vaccine.

METHODSWild type CTB coding gene was amplified and cloned into prokaryotic expression vector pET-30a, and the recombinant CTB was expressed in the presence of different concentration of chloramphenicol and isopropyl β-D-thiogalactoside. Purified recombinant CTB was mixed with HIV-1 AE2f tat-rev-integrase-vif-nef fusion gene DNA vaccine and female BALB/c mice were vaccinated with a DNA priming-recombinant vaccinia vectored vaccine boosting regimen through intramuscular injection. Interferon γ (IFN-γ) enzyme-linked immunospot (Elispot) assay was used to read out the specific T-cell immunity.

RESULTSChloramphenicol was essential for the efficient expression of recombinant CTB (rCTB) in pET-30a/BL21 (DE3) system and could be optimized at the concentration of 0.625 µg/ml in the presence of chloramphenicol. The purified rCTB could bind with GM1 efficiently. INF-γ Elispot data showed the T-cell response induced in CTB adjuvanted group ((734 ± 240) spot forming cells/10(6) splenocytes) was higher than that induced by non-adjuvanted ((520 ± 150) spot forming cells/10(6) splenocytes), all responses against different antigens were enhanced in parallel.

CONCLUSIONCTB could be efficiently expressed in the presence of chloramphenicol and purified CTB is functional and capable of enhancing the specific T cell responses elicited by DNA vaccine, the mechanism needs to be explored in the future.

Adjuvants, Immunologic ; pharmacology ; Animals ; Blotting, Western ; Chloramphenicol ; pharmacology ; Cholera Toxin ; metabolism ; Electrophoresis, Polyacrylamide Gel ; Escherichia coli ; drug effects ; metabolism ; Female ; Mice ; Mice, Inbred BALB C ; Recombinant Fusion Proteins ; genetics ; immunology ; metabolism ; Vaccines, DNA ; genetics ; immunology ; metabolism

Hydrophilic low molecular drugs, peptides and proteins, which are always poor in bioavailability, are mainly absorbed through the paracellular way in which the tight junction is the elementary framework. The tight junctions are a multiple unit structure composed of multiprotein complex that affiliates with the underlying apical actomyosin ring. Tight junction proteins are identified including transmembrane proteins (occludin, claudin and JAM) , cytoplasmic plaque proteins (ZO-1, ZO-2, ZO-3 and cingulin) and cytoskeleton. Traditional absorption enhancers can usually impair mucous membranes which constraint the utilization of these enhancers. Recently, with the increasing knowledge of the structure and function of tight junctions, many new absorption enhancers have been developed such as NO donor, CPE, Zot, and so on. In vivo and in vitro studies have shown that these enhancers could be effectively used to increase the absorption of paracellular markers and low bioavailable drug across intestinal epithelium with lower side effect. In short, the transient opening of the tight junctions by these enhancers provides new ideas that could help in novel drug delivery of therapeutic agents.
Animals ; Biological Availability ; Cell Adhesion Molecules ; metabolism ; Cholera Toxin ; pharmacology ; Claudin-1 ; Cytoskeleton ; metabolism ; Decanoic Acids ; pharmacology ; Drug Delivery Systems ; Enterotoxins ; pharmacology ; Humans ; Intestinal Absorption ; drug effects ; Membrane Proteins ; metabolism ; Nitric Oxide Donors ; pharmacology ; Occludin ; Phosphoproteins ; metabolism ; Receptors, Cell Surface ; metabolism ; Tight Junctions ; metabolism ; physiology ; Zonula Occludens-1 Protein

No abstract available.
Animal ; Biological Transport/physiology ; Biological Transport/drug effects ; Cholera/metabolism ; Diglycerides/pharmacology ; Epithelial Cells*/virology ; Epithelial Cells*/microbiology ; Epithelial Cells*/metabolism ; Escherichia coli ; Escherichia coli Infections/metabolism ; Estrenes/pharmacology ; In Vitro ; Indoles/pharmacology ; Influenza/metabolism ; Intestinal Mucosa/cytology ; Maleimides/pharmacology ; Mice ; Phosphodiesterase Inhibitors/pharmacology ; Pyrrolidinones/pharmacology ; Respiratory Mucosa/cytology ; Sodium Channels/metabolism* ; Staurosporine/pharmacology ; Vibrio cholerae

Previously it has been shown that persistent activation of the stimulatory adenylyl cyclase pathway with cholera toxin (CT) downregulates the Gs alpha polypeptide (80%) in a cAMP-independent manner in C6 glioma cells (Shah, 1997). This study was conducted to examine the short and long term effects of CT on the regulation of pertussis toxin-sensitive and -insensitive G proteins and their transcripts in C6 glioma cells. Treatment of C6 cells with CT (100 ng/ml) up to 16 h had no effect on either Gi or Gq/11 alpha proteins. However, prolonged exposure (24-48 h) caused increased expression of Gi (20-30%) and Gq/11 alpha proteins (40%). Urea gradient gels, which can separate Gq alpha and G11 alpha proteins, revealed that prolonged CT treatment increased the expression of both of these G proteins. The CT-mediated enhanced expression of Gq alpha and G11 alpha proteins was accompanied by increased mRNA levels of these proteins as determined by RT/PCR. Cyclic-AMP elevating agents like forskolin (10 microM) and db-cAMP (1 mM) mimicked the effect of CT on Gi but not Gq/11 alpha proteins. These studies show long term cAMP-dependent regulation of Gi and cAMP-independent expression of Gq/11 alpha proteins in C6 glioma cells.
Animal ; Blotting, Western ; Bucladesine/pharmacology ; Cholera Toxin/pharmacology* ; Cyclic AMP-Dependent Protein Kinases/metabolism ; Forskolin/pharmacology ; GTP-Binding Proteins/genetics* ; GTP-Binding Proteins/biosynthesis ; Gene Expression Regulation* ; Glioma ; Membrane Proteins/analysis ; RNA, Messenger/metabolism ; RNA, Messenger/genetics ; Rats ; Reverse Transcriptase Polymerase Chain Reaction

OBJECTIVETo express and purify Hap protein of nontypeable Haemophilus influenzae (NTHi) in prokaryotic system, and study its immunogenicity and adhesive activity.

METHODHap protein was expressed in E.coli BL21 with pET32a (+)-Hap and purified by affinity chromatography. The adhesive activity of the recombinant Hap protein was observed in competitive adhesion assay using scanning electron microscope and bacterial counting. BALB/C mice were immunized intranasally with the purified recombinant Hap protein and cholera toxin B subunit (CT-B), and anti-Hap IgA and IgG were detected by enzyme-linked immunosorbent assay.

RESULTSSDS-PAGE analysis showed a single band of the target protein, whose purity reached 85% according to the result of Gel analysis software. The concentration of the protein was 3.2 g/L after ultrafiltration and condensation. Competitive adhesion assay showed that compared with control group, the recombinant Hap protein significantly inhibited the adhesion of NTHi to ECM (P<0.01). Compared with Hap immunization alone, immunization with Hap combined with CT-B resulted in significantly higher titers of anti-Hap IgG and IgA in mice (P<0.05).

CONCLUSIONHighly purified recombinant Hap protein has been obtained in a prokaryotic system and shows good immunogenic and adhesive activities. These results will establish the basis for further study of NTHi vaccine.

Adhesiveness ; Animals ; Bacterial Outer Membrane Proteins ; biosynthesis ; genetics ; immunology ; Cholera Toxin ; immunology ; Escherichia coli ; genetics ; metabolism ; Haemophilus Infections ; prevention & control ; Haemophilus influenzae ; metabolism ; Immunization ; Immunoglobulin A ; blood ; Immunoglobulin G ; blood ; Mice ; Mice, Inbred BALB C ; Recombinant Proteins ; biosynthesis ; genetics ; immunology ; Serine Endopeptidases ; biosynthesis ; genetics ; immunology