Expression and Purification of Tetanus Toxin Fragment C in Escherichia coli BL21(DE3).

BACKGROUND: Tetanus is an infectious disease caused by Clostridium secreting tetanus toxin in anaerobic environment. The fragment C of Tetanus toxin (TTc) has been widely studied as a candidate vaccine to replace the existing tetanus toxoid vaccine. OBJECTIVE: In this study, we established a simple method to purify recombinant protein TTc with ion-exchange chromatography from Escherichia coli expression systems. METHODS: The TTc gene sequence was cloned into pET26b (+) vector and transferred to E. coli BL21 (DE3) for expression. The fermentation conditions (IPTG concentration, Induction temperature, Induction time) were optimized to obtain more soluble proteins. The soluble proteins were purified by Anion exchange chromatography and Cation exchange chromatography. The sequence of columns in the purification process was discussed. Finally, the stability of purified TTc protein were determined, the secondary structure of the purified TTc protein was determined by circular dichroism. The molecular weight of the purified TTc protein was determined by liquid chromatograph- mass spectrometer. Furthermore, we verified the immunogenicity of the purified protein in mice. RESULTS: The purity of TTc improved from 34% to 88% after the first anion exchange column, and the final yield of recombinant TTc (purity > 95%) can reach 84.79% after the following cation exchange chromatography. The recombinant TTc had a molecular weight of 51.737 KDa, was stable at 4 °C and weak alkaline environment, was a ß-sheet secondary structure, and had strong immunogenicity. CONCLUSION: The purification method we developed might be an efficient method for the industrial production of tetanus recombinant TTc vaccine.

Tetanus toxin fragments and Bcl-2 fusion proteins: cytoprotection and retrograde axonal migration.

BACKGROUND: Tetanus neurotoxin (TeNT) is taken up at nerve terminals and undergoes retrograde migration. The toxic properties of TeNT reside in the toxin light chain (L), but like complete TeNT, the TeNT heavy chain (TTH) and the C-terminal domain (TTC) alone can bind and enter into neurons. Here, we explored whether atoxic fragments of TeNT could act as drug delivery vehicles in neurons. In this study, we used Bcl-2, a protein known to have anti-apoptotic properties in vivo and in vitro, as a parcel to couple to TeNT fragments. RESULTS: We expressed Bcl-2 and the TTC fragments alone, and also attempted to express fusion proteins with the Bcl-2 coupled at the N-terminus of TTH (Bcl2-TTH) and the N- and C-terminus of TTC (TTC-Bcl2 and Bcl2-TTC) in mammalian (Cos7 cells) and Escherichia coli systems. TTC and Bcl-2 were efficiently expressed in E. coli and Cos7 cells, respectively, but Bcl-2 and the fusion proteins did not express well in E. coli. The fusion proteins were also not expressed in Cos7 cells. To improve the yield and purity of the fusion protein, we genetically deleted the N-terminal half of TTC from the Bcl2-TTC fusion to yield Bcl2-hTTC. Purified Bcl2-hTTC exhibited neuronal binding and prevented cell death of neuronal PC12 cells induced by serum and NGF deprivation, as evidenced by the inhibition of cytochrome C release from the mitochondria. For in vivo assays, Bcl2-hTTC was injected into the tongues of mice and was seen to selectively migrate to hypoglossal nuclei mouse brain stems via retrograde axonal transport. CONCLUSIONS: These results indicate that Bcl2-hTTC retains both Bcl-2 and TTC functions and therefore could be a potent therapeutic agent for various neurological conditions.

Clarification of vaccines: An overview of filter based technology trends and best practices.

Vaccines are derived from a variety of sources including tissue extracts, bacterial cells, virus particles, recombinant mammalian, yeast and insect cell produced proteins and nucleic acids. The most common method of vaccine production is based on an initial fermentation process followed by purification. Production of vaccines is a complex process involving many different steps and processes. Selection of the appropriate purification method is critical to achieving desired purity of the final product. Clarification of vaccines is a critical step that strongly impacts product recovery and subsequent downstream purification. There are several technologies that can be applied for vaccine clarification. Selection of a harvesting method and equipment depends on the type of cells, product being harvested, and properties of the process fluids. These techniques include membrane filtration (microfiltration, tangential-flow filtration), centrifugation, and depth filtration (normal flow filtration). Historically vaccine harvest clarification was usually achieved by centrifugation followed by depth filtration. Recently membrane based technologies have gained prominence in vaccine clarification. The increasing use of single-use technologies in upstream processes necessitated a shift in harvest strategies. This review offers a comprehensive view on different membrane based technologies and their application in vaccine clarification, outlines the challenges involved and presents the current state of best practices in the clarification of vaccines.

Detection of Clostridium tetani in human clinical samples using tetX specific primers targeting the neurotoxin.

Tetanus resulting from ear injury remains an important health problem, particularly in the developing world. We report the successful detection of Clostridium tetani using tetX specific primers targeting the Cl. tetani neurotoxin. The sample was obtained from an ear discharge of a case of otogenic tetanus in a 2-year-old male child. Based on the culture results of the ear discharge, Gram staining and virulence testing by genotyping, a diagnosis of tetanus was confirmed. This is the first report from India on the successful detection of Cl. tetani in a human clinical sample using tetX specific primers targeting the Cl. tetani neurotoxin.

Botulinum neurotoxin homologs in non-Clostridium species.

Clostridial neurotoxins (CNTs) are the deadliest toxins known and the causative agents of botulism and tetanus. Despite their structural and functional complexity, no CNT homologs are currently known outside Clostridium. Here, we report the first homologs of Clostridium CNTs within the genome of the rice fermentation organism Weissella oryzae SG25. One gene in W. oryzae S25 encodes a protein with a four-domain architecture and HExxH protease motif common to botulinum neurotoxins (BoNTs). An adjacent gene with partial similarity to CNTs is also present, and both genes seem to have been laterally transferred into the W. oryzae genome from an unknown source. Identification of mobile, CNT-related genes outside of Clostridium has implications for our understanding of the evolution of this important toxin family.

Results of an international transferability study of the BINACLE (binding and cleavage) assay for in vitro detection of tetanus toxicity.

Tetanus vaccines contain detoxified tetanus neurotoxin. In order to check for residual toxicity, the detoxified material (toxoid) has to be tested in guinea pigs. These tests are time-consuming and raise animal welfare issues. In line with the "3R" principles of replacing, reducing and refining animal tests, the "binding and cleavage" (BINACLE) assay for detection of active tetanus neurotoxin has been developed as a potential alternative to toxicity testing in animals. This in vitro test system can discriminate well between toxic and detoxified toxin molecules based on their receptor-binding and proteolytic characteristics. Here we describe an international study to assess the transferability of the BINACLE assay. We show that all participating laboratories were able to successfully perform the assay. Generally, assay variability was within an acceptable range. A toxin concentration-dependent increase of assay signals was observed in all tests. Furthermore, participants were able to detect low tetanus neurotoxin concentrations close to the estimated in vivo detection limit. In conclusion, the data from this study indicate that the methodology of the BINACLE assay seems to be robust, reproducible and easily transferable between laboratories. These findings substantiate our notion that the method can be suitable for the routine testing of tetanus toxoids.

Enhanced expression of soluble recombinant tetanus neurotoxin Hc in Escherichia coli as a tetanus vaccine candidate.

The expression of the carboxyl fragment of the heavy chain of tetanus neurotoxin (TeNT-Hc) in Escherichia coli has been hampered by the unusually high AT content and the presence of rarely used codons by Clostridium. The gene encoding TeNT-Hc was optimized for E. coli by replacing rare codons and decreasing the AT pairs from 72.57% to 52.47%. The reconstructed gene was expressed in E. coli BL21(DE3) and resulted in a soluble product which was about 46% of the total bacterial protein. TeNT-Hc produced in a 42 L fermentor was purified to >95% at 87 g/kg of cell paste (approximately 333 mg/L). BALB/c mice vaccinated with three bi-weekly doses of TeNT-Hc with Freund's adjuvant were fully protected against an intraperitoneally challenge of 2 × 10(3) 50% lethal doses (LD(50)s) of tetanus neurotoxin. NIH mice vaccinated with TeNT-Hc adsorbed to aluminum hydroxide gel adjuvant demonstrated a potency of 168 IU/mL, which was 2 times higher than the national standard for tetanus vaccines. These results suggest that TeNT-Hc may be a promising second-generation vaccine candidate for clinical use against tetanus neurotoxin.

Escherichia coli-based production of a tumor idiotype antibody fragment--tetanus toxin fragment C fusion protein vaccine for B cell lymphoma.

The unique immunoglobulin idiotype expressed on the surface of B lymphoma cells can be used as an effective antigen in tumor-specific vaccines when fused to immunostimulatory proteins and cytokines. A DNA vaccine encoding for an idiotype antibody single chain Fv (scFv) fragment fused to the Tetanus Toxin Fragment C (TTFrC) has been shown to induce protective anti-tumor responses. Protein-based strategies may be more desirable since they provide greater control over dosage, duration of exposure, and in vivo distribution of the vaccine. However, production of fusion protein vaccines containing complex disulfide bonded idiotype antibodies and antibody-derived fragments is challenging. We use an Escherichia coli-based cell-free protein synthesis platform as well as high-level expression of E. coli inclusion bodies followed by refolding for the rapid generation of an antibody fragment - TTFrC fusion protein vaccine. Vaccine proteins produced using both methods were shown to elicit anti-tumor humoral responses as well as protect from tumor challenge in an established B cell lymphoma mouse model. The development of technologies for the rapid production of effective patient-specific tumor idiotype-based fusion protein vaccines provides opportunities for clinical application.

Cloning and expression of a region of vesicle associated membrane protein2 (VAMP2) gene and its use as a recombinant peptide substrate for assaying clostridial neurotoxins in contaminated biologicals.

An assay for the endopeptidase activities of clostridial neurotoxins in contaminated biotherapeutic products has been developed. Based on a synthetic peptide substrate representing amino acid residues 60-94 of the intracellular vesicle associated membrane protein2 (VAMP2), RT-PCR was used to amplify the VAMP2 sequence. The extended insert was digested with EcoRI and SalI and ligated into pGEX4T-1 vector for construction of the pGEX4T-1/VAMP plasmid for expressing in Escherichia coli a fusion protein linked to glutathione S-transferase (GST). The fusion protein was purified by affinity chromatography and used in an ELISA assay for comparison with the commercially available synthetic VAMP peptide and rabbit polyclonal antiserum. The identity of the immunoreactivity of recombinant VAMP2 protein with the chemically synthesized peptide was demonstrated by western blot. Our results indicated that recombinant VAMP2 peptide not only reacted with specific polyclonal antibody in a dose-dependent manner, without any remarkable difference observed between the reactivity of the fusion protein and commercial VAMP2 segment peptide, but also cleaved by botulinum neurotoxin type B (BONT/B) after endopeptidase assay. Thus, recombinant VAMP2 could serve as a replacement for VAMP2 synthetic peptide, potentially useful in endopeptidase assays for replacement of the currently used mouse bioassay for clostridial neurotoxins contaminating biotherapeutic products.

[Expression, purification of tetanus toxin C fragment/cardiotrophin-1 recombinant fusion protein, target delivery to CNS and neurotrophy biology ability].

OBJECTIVE: Expression, purification of tetanus toxin C fragment/cardiotrophin-1 recombinant fusion protein (CT-1/TTC) in BL21 (DE3) E. coli, examined whether tetanus toxin C fragment mediate the cardiotrophin-1 target delivery to the central nervous system and the cardiotrophin-1 has the neurotrophic ability. METHODS: Induction by IPTG, the fusion protein was expressed and then purified by GST affinity agarose. The interest protein was viewed by SDS-PAGE, further characterized by Western Blot Rat sciatic nerve transected model was selected. Using drug by nerve-regeneration-chamber and intramuscular injection. Execute these animals one week after the operation. The L4-L6 segments of the spinal cord were harvested after transaortic perfusion with 4% paraformaldehyde. The freeze sections of spinal tissues were stained with immunohistochemistry method. And select the new born SD rat sciatic nerve transected model, using CT-1/TTC fusion protein by muscle injection. Execute these animals one week after the operation. The L4-L6 segments of the spinal cord were harvested after transaortic perfusion with 4% paraformaldehyde. The freeze sections of spinal tissues were stained by Nissl's staining. RESULTS: After induction, the fusion protein was about 15% of the total protein and the soluble part was predominant. Purified by GST fusion protein column, the interest protein's concentration is 2.7 g/L. The CT-1/TTC fusion protein was found in lumbar intumescentia by immunohistochemistry method. And after sciatic nerve transected, the numbers of cornu anterius medullae spinalis motoneurons in L4-L6 segments, compared to CT-1/TTC protein grope, have a lower survival rate. CONCLUSIONS: The recombinant CT-1/TTC protein can be expressed and purified in BL21 (DE3) E. coli. This fusion protein has two biological activities of targeting delivery to central nervous system and protecting the cornu anterius medullae spinalis motoneurons.

[Study of four kits used for titration of tetanus antibody for selection of plasma donors intended to fractionation]. / Etude de quatre trousses de titrage des anticorps antitétaniques pour la sélection des plasmas destinés au fractionnement (LFB).

UNLABELLED: Antitetanus antibodies titration is carried out by French National Blood Services (FNBSs) with the aim of seeking donors whose title of antibodies are greater or equal to 8 IU/ml. Different kits are used: ELISA antitetanus toxoid IgG (The Binding Site), ELISAT (Diagast), tetanus toxoid IgG ELISA (Diamed), ELISA IgG tetanus (Ingen). As the results obtained using these different reagents show some discrepancies with the control results carried out by the Laboratoire Français des Biotechnologies (LFB), it appeared necessary to harmonize the selection practices. With this intention a study of the different kits was initiated. METHOD: Different samples were used during this evaluation: (1) the Reference Control (RC) used by the FNBS; (2) a serum sample of high title; (3) a range of dilution of national standard. The following tests were carried out: (1) robustness with the evaluation of the contamination and the board effect; (2) linearity and repeatability (eight deposits of each standard, RC and points of national standard dilutions); (3) reproducibility; (4) homogeneity. After automatic dilution of the samples, the plates were then processed according to the protocol of the manufacturer. RESULTS: The study gives the CV in percentage of repeatability and reproducibility, the values of the standards provided as well as the bias compared to the RC and the uncertainty of measurements. CONCLUSION: This study gave the possibility to rank each kit compared to RC and to specify the variations which surround each result. This variation can explain the discrepancy of conformity of plasma when title is close to the threshold of selection.

Sm14 of Schistosoma mansoni in fusion with tetanus toxin fragment C induces immunoprotection against tetanus and schistosomiasis in mice.

We have constructed vectors that permit the expression in Escherichia coli of Schistosoma mansoni fatty acid-binding protein 14 (Sm14) in fusion with the nontoxic, but highly immunogenic, tetanus toxin fragment C (TTFC). The recombinant six-His-tagged proteins were purified by nickel affinity chromatography and used in immunization and challenge assays. Animals inoculated with TTFC in fusion with or coadministered with Sm14 showed high levels of tetanus toxin antibodies, while animals inoculated with Sm14 in fusion with or coadministered with TTFC showed high levels of Sm14 antibodies. In both cases, there were no changes in the type of immune response (Th2) obtained with the fusion proteins compared to those obtained with the nonfused proteins. Mice immunized with the recombinant proteins (TTFC in fusion with or coadministered with Sm14) survived the challenge with tetanus toxin and did not show any symptoms of the disease. Control animals inoculated with either phosphate-buffered saline (PBS) or Sm14 died with severe symptoms of tetanus after 24 h. Mice immunized with the recombinant proteins (Sm14 in fusion with or coadministered with TTFC) showed a 50% reduction in worm burden when they were challenged with S. mansoni cercariae, while control animals inoculated with either PBS or TTFC were not protected. The results show that the expression of other antigens in fusion at the carboxy terminus of TTFC is feasible for the development of a multivalent recombinant vaccine.

Expressing and purifying an anti-atherosclerosis polypeptide vaccine in Escherichia coli.

A chimeric polypeptide of TTP-CETPC was successfully expressed as inclusion bodies in Escherichia coli by fusing it with the C-terminus of asparaginase and a basic amino acid-rich peptide (KR). After partially purified by washing with 0.5% (v/v) Triton X-100 in 10 mM PB, the pellet was solubilized in 8 M urea. The solution was precipitated with single volume and double volumes of cold ethanol for removing impurities. The fusion protein in solution was precipitated with triple volumes of ethanol to increase purity and then hydrolyzed with 50 mM hydrochloric acid at 55 degrees C for 72 h. The TTP-CETPC polypeptide was released after the unique acid-labile aspartylprolyl bond in the fusion protein was cleaved by acid. After impurities were removed by adjusting the hydrolysis solution pH to 9.45 and then to 8.37, the TTP-CETPC polypeptide was further purified by DEAE-cellulose column. The TTP-CETPC containing fractions were eluted at 60-80 mM NaCl. The purified TTP-CETPC cysteines were oxidized to form into intermolecular disulfide bonded dimers for immunizing mice. Specific anti-CETP antibodies in mice serum were assayed by ELISA and Western blot to verify that antibodies against CETP had been successfully induced and lasted for more than seventeen weeks in vivo.

High-level expression of tetanus toxin fragment C-thioredoxin fusion protein in Escherichia coli.

An insert of Clostridium tetani DNA corresponding to fragment C of tetanus toxin was amplified by PCR. This 1.4 kb fragment was cloned into the high-expression vector pET32a, under control of the T7 promoter. Expression of this plasmid in Escherichia coli BL21(DE3) resulted in the production of a fusion protein ( approximately 62 kDa) consisting of 112 amino acids of thioredoxin and approximately 450 amino acids of fragment C. This fusion protein was recognized by anti-tetanus toxoid antiserum in an ELISA and on immunoblots. The recombinant fragment-C-thioredoxin protein was purified significantly in one step by Ni(2+)-chelate Sepharose, the final yield being approximately 35 mg/l. Immunization of animals with the recombinant protein produced antibodies that were able to recognize the tetanus toxin. By using this gene-fusion expression system we produced soluble fragment C of tetanus toxin in a high yield, preventing many problems inherent in the use of other expression systems that produce either insoluble fragment C in inclusion bodies, or a soluble form, but in low yield, using E. coli as the expression host.

Development and validation study for the chromatographic purification process for tetanus anatoxin on Sephacryl S-200 High Resolution.

The tetanus purified anatoxin is used in the preparation of multiple immunoprophylactics. WHO (World Health Organization) specifies that the tetanus anatoxin must exhibit a degree of purity greater than or equal to 1,000 Lf/mg protein nitrogen (PN). Today liquid chromatography is a well established technique for the purification of tetanus anatoxin and several different methods are used in production scale. On a small scale, we purified tetanus anatoxin on Sephacryl S-200 High Resolution (gel filtration) and we obtained a successful high-yield purification. On the basis of these results, by combining conventional tangential flow filtration (TFF) at 50,000 N.M.W.L. (Nominal Molecular Weight Limit) ultrafiltration membrane with gel filtration on Sephacryl S-200 High Resolution, we have been able to purify 14 lots of tetanus anatoxin using the Bioprocess System (Amersham Pharmacia Biotech) to a large scale operation. Using this method, 77,401,332 doses of tetanus toxoid were prepared in 14 consecutive lots, supporting the reproducibility and reliability of the method presented here.

Recombinant and truncated tetanus neurotoxin light chain: cloning, expression, purification, and proteolytic activity.

Tetanus neurotoxin (TeNT) consists of two disulfide-linked polypeptide chains, heavy (H) and light (L). The L chain is a zinc endopeptidase protein highly specific for vesicle-associated membrane protein (VAMP), which is an essential component of the exocytosis apparatus. Here we describe the cloning of the L chain of TeNT from Clostridium tetani strain Y-IV-3 (WS 15) and its expression in Escherichia coli as a glutathione S-transferase fusion protein. The full-length recombinant L chain, corresponding to residues 1-457, was obtained as a mixture of proteins of slightly different mass with identical N-terminal ends. To obtain a product useful for structural analysis and crystallization, a COOH-terminally truncated L chain (residues 1-427) was cloned, expressed, and purified with high yield. This truncated L chain is more active than the full-length and wild-type proteins in the hydrolysis of VAMP. Preliminary experiments of crystallization of the truncated recombinant L chain gave encouraging results.

Purification of intracellular compartments involved in antigen processing: a new method based on magnetic sorting.

In the present study, we describe a method to specifically isolate intracellular compartments containing endocytosed antigen. We have demonstrated that isolated compartments represent a small proportion of the intracellular material, highly enriched in antigen. Antigen-containing vesicles are specifically sorted from other intracellular compartments, such as endoplasmic reticulum or Golgi apparatus, and from the plasma membrane. They remain functional in vitro since they can be acidified, and the antigen inside has been found to be partially proteolysed. In macrophages, kinetic analysis has revealed that the antigen is first found in compartments of endosomal density, carrying Rab 5 and Rab 7, then in late compartments of lysosomal density, which are rich in proteases. The global protein content of the compartments was mapped by two-dimensional electrophoresis. In B lymphocytes, this method has allowed the isolation of endocytic compartments emerging from receptor-mediated endocytosis of the antigen. After 2 h of chase, the antigen reached vesicles containing large amounts of MHC-class II molecules, invariant chain and human leucocyte antigen-DM, where peptide loading can occur.

Crystallization and preliminary X-ray analysis of tetanus neurotoxin C fragment.

Two crystal forms of recombinant tetanus neurotoxin C fragment have been obtained. The C fragment corresponds to the C-terminal 451 amino-acid residues of tetanus neurotoxin and is the subunit responsible for receptor binding by the toxin. Both forms belong to space group P212121. Form I has unit-cell dimensions of a = 71.3, b = 79.7, c = 94.0 A and produces thin plate crystals. Form II has unit-cell dimensions of a = 67.4, b = 79.7, c = 91.1 A and produces thick rod-shaped crystals. Diffraction data to 2.6 A have been collected from form II crystals.

Expression of tetanus toxin fragment C.

1. The yield of fragment C was only modestly affected by Mut phenotype, and the site and type of integration event. 2. Fragment C accumulation was closely correlated with gene dosage and maximal expression levels required high gene copy number. 3. Yields were greatly increased in controlled fermenters, compared to shake-flasks, owing to the high cell density achieved and to an increased efficiency of induction (2.5- to 10-fold). 4. In fermenter inductions of a 14-copy strain, fragment C accumulated to 27% of total protein, giving an estimated yield of 12 g/L. 5. Considerable clonal variation in the level of expression occurred with transplacement transformants, and this was owing to a diversity of different integration events and to differences in gene copy number. 6. These multicopy transplacement events occur by in vivo circularization of transforming DNA fragments followed by repeated single-crossover integration. This is presumably a general phenomenon, such that it should be possible to obtain multicopy integrants from all P. pastoris transplacement transformations.