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Protective murine monoclonal antibodies to tetanus toxin.

Monoclonal antibodies against tetanus toxin were generated by fusion of mouse NS-1 myeloma cells with spleen cells from BALB/C mice immunized with tetanus toxoid. Twenty seven hybridomas against tetanus toxin were obtained. Six hybridoma clones, designated as 1A6B12, 1H7D9, 3A8G9, 3A9F2, 3F9H9, 4A6D11 were selected for further studies. All of them were IgG1, k chain and bound specifically to tetanus toxin and toxoid. All six clones were injected intraperitoneally into pristane-primed BALB/C mice. Antibodies with titer up to 10(6) were obtained in the ascites. Results obtained from in vivo neutralization test showed that 1A6B12, 3A8G9, 3F9H9, 4A6D11 mAbs did have neutralizing activities against tetanus toxin. Monoclonal antibody 4A6D11 had the strongest neutralizing activity. 4A6D11 were purified from ascites by DEAE-52 ion exchange chromatography. Comparing to U.S.A. standard antitetanus toxin antiserum, 50 micrograms purified 4A6D11 mAb had 1 international unit neutralizing activity. The purified 4A6D11 mAb was also coupled to cyanogen bromide-activated sepharose to make an affinity column. Pure tetanus toxin can be obtained by passing crude tetanus toxin through this column and eluting the adsorbed toxin with 4M urea. Large scale purified tetanus toxin could be obtained by this method.

Animals↗

Gangliosides in phospholipid bilayer membranes: interaction with tetanus toxin.

The interaction between tetanus toxin and its fragments with gangliosides and negatively charged phosphatidylglycerols has been studied in phosphatidylcholine host membranes by protein circular dichroism measurement, calorimetry to determine lipid phase transitions, and by fluorescence spectroscopy to follow the toxin-induced pore formation by measuring the release of intravesicular entrapped dye. CD-spectroscopic secondary structure analysis showed conformational change of the toxin only in the presence of GT1b clearly demonstrating the involvement of the ganglioside headgroups for this lipid-protein-interaction. In a dot-blot analysis we showed that fragment C binds to GT1b in reconstituted vesicles and that this fragment is then accessible to a fragment C specific antibody which is only possible if fragment C is exposed at least partially on the surface of the vesicle. Our calorimetric study demonstrates the preferential binding of tetanus toxin to ganglioside GT1b. However, this protein is also able to bind to other gangliosides and also to negatively charged phospholipids causing phase separation due to electrostatic interaction. Since tetanus toxin preferentially binds short chain phosphatidylglycerol, we conclude that the protein adopts lipids with respect to charge, head group structure and chain length from the bulk phase. One consequence of this lipid-protein interaction is the ability of tetanus toxin to permeabilize lipid vesicles. Pore formation is favoured in the presence of GT1b in phosphatidylcholine membranes but only at a sufficiently high enough ganglioside content. Gangliosides others than GT1b are less effective in pore formation. In the presence of negatively charged phosphatidylglycerol tetanus toxin causes a dye release which in contrast to GT1b-containing vesicles is not saturable. We conclude that tetanus toxin acts in combination with a given number of GT1b molecules. Twenty ganglioside molecules are found to be necessary to form the stable pore. Other negatively charged lipids also cause the toxin to intercalate into the membrane but in this case the release velocity is determined by the formation of membrane defects.

Circular Dichroism↗

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.

Animals↗

An attempt to activate the spontaneous motility in chick embryos with tetanus toxin.

The effect of tetanus toxin on spontaneous motor activity was studied in chick embryos between the 11th and 19th day of incubation. The toxin--dose 20 mg/kg egg weight ( = 2.86 X 10(3) mouse MLD) in 25 microliters isotonic NaCl solution--was injected into the tibial or the wing muscles. Tetanus toxin induced demonstrable activation of embryonic motility from the 15th day of incubation onwards. Activation attained 155-200% of resting activity. The activating effect was manifested for the first time by motor paroxysms in 17-day and particularly 19-day embryos. Tetanus toxin activation was effectively depressed by glycine (100 mg/kg e.w.) and GABA (100 mg/kg e.w.), the former having a stronger effect than the latter. The effect of tetanus toxin on spinal embryos was relatively more pronounced, while the depressant effect of the inhibitory amino acids (especially glycine) was weaker. The results are evaluated as further evidence that central inhibitory mechanisms are connected up in regulation of the spontaneous motor output activity of chick embryos on about the 15th day of incubation.

Animals↗

Lymphocyte response to tetanus toxin T-cell epitopes: effects of tetanus vaccination and concurrent malaria prophylaxis.

Synthesized T-cell epitopes of tetanus toxin are universally immunogenic and serve to enhance immune response when they are used as vaccine carriers of B-cell epitopes. The immunogenicity of the P2, P30, and P2P30 T-cell epitopes of tetanus toxin and whole tetanus toxoid (TT) was evaluated by in vitro proliferation assay of lymphocytes from men with no history of tetanus vaccination who were enrolled in a malaria prophylaxis trial. The enhancement of immune response by tetanus vaccination (Td) and possible antagonism by the antimalarial drugs, was measured by pre- and post-Td comparisons within and between immunized prophylaxis groups (primaquine, chloroquine, placebo) and a nonimmunized control group. Constructs demonstrated low immunogenicity relative to TT in all groups. Relative to both control and its own baseline, the immunized primaquine prophylaxis group was distinct in demonstrating significantly increased proliferation against all three subunits and at both high (30 microg ml(-1)) and low (3 microg ml(-1)) concentrations. Immunization elicited significantly increased proliferation responses by placebo and chloroquine prophylaxis groups against only the P2P30 construct. Despite these significant post-Td changes, a low concentration of TT 0.1 microg ml(-1)) stimulated proliferation 7-10 times over that induced by the greatest concentration of the constructs.

Adult↗

The effects of tetanus toxin on the orbicularis oculi muscle.

PURPOSE: Tetanus toxin can cause localized neuromuscular weakness, but it also can produce systemic tetany. The action of tetanus toxin on the orbicularis muscle has not been studied in animals immunized to prevent systemic tetany. Our objective was to determine whether tetanus toxin could be used to treat orbicularis oculi muscle spasms. METHODS: We analyzed the clinical, electrophysiologic, and histopathologic effects of tetanus toxin injected into the orbicularis oculi muscle of rabbits with passive immunity to tetanus toxin. In six rabbits, the orbicularis oculi function in both eyes was assessed clinically, and the baseline orbicularis oculi muscle action potential was measured physiologically with electromyography (EMG). The rabbits then were immunized against tetanus toxin with tetanus immunoglobulin for immediate and definitive immunity. Tetanus toxin was injected into the left orbicularis oculi muscles, leaving the right eyes as controls. Ten days later, the rabbits were again assessed by clinical examination and with EMGs on both the injected side and the noninjected side. The animals were killed at 14 days, and the orbicularis muscle was removed from both sides. The injected and control tissues were examined microscopically for signs of neuromuscular denervation. RESULTS: All six rabbits showed weakness in eye closure on the side injected with tetanus toxin. In addition, four rabbits developed complete ear ptosis on the tetanus toxin injected side because of spread of the toxin to adjacent ear muscles. EMGs showed both a denervation of the orbicularis oculi muscle and a poor blink potential on the side injected with tetanus toxin. Histopathologic studies of the orbicularis oculi muscle injected with tetanus toxin showed angulation of both slow and fast types of muscle fibers compatible with neuromuscular denervation. CONCLUSIONS: Tetanus toxin can cause localized orbicularis oculi weakness, as documented clinically, physiologically, and microscopically, without producing systemic tetany in immunized rabbits. Tetanus toxin may have a potential application in the treatment of blepharospasm and hemifacial spasm.

Action Potentials↗

Ca2+ or Sr2+ partially rescues synaptic transmission in hippocampal cultures treated with botulinum toxin A and C, but not tetanus toxin.

Botulinum (BoNT/A-G) and tetanus toxins (TeNT) are zinc endopeptidases that cleave proteins associated with presynaptic terminals (SNAP-25, syntaxin, or VAMP/synaptobrevin) and block neurotransmitter release. Treatment of hippocampal slice cultures with BoNT/A, BoNT/C, BoNT/E, or TeNT prevented the occurrence of spontaneous or miniature EPSCs (sEPSCs or mEPSCs) as well as the [Ca2+]o-independent increase in their frequency induced by phorbol ester, 0.5 nM alpha-latrotoxin, or sucrose. [Ca2+]o-independent and -dependent release thus requires that the target proteins of clostridial neurotoxins be uncleaved. In contrast, significant increases in mEPSC frequency were produced in BoNT-treated, but not TeNT-treated, cultures by application of the Ca2+ ionophore ionomycin in the presence of 10 mM [Ca2+]o. The frequency of sEPSCs was increased in BoNT-treated, but not TeNT-treated, cultures by increasing [Ca2+]o from 2.8 to 5-10 mM or by applying 5 mM Sr2+. Large Ca2+ and Sr2+ influxes thus can rescue release after BoNT treatment, albeit less than in control cultures. The nature of the toxin-induced modification of Ca2+-dependent release was assessed by recordings from monosynaptically coupled CA3 cell pairs. The paired-pulse ratio of unitary EPSCs evoked by two presynaptic action potentials in close succession was 0.5 in control cultures, but it was 1.4 and 1.2 in BoNT/A- or BoNT/C-treated cultures when recorded in 10 mM [Ca2+]o. Log-log plots of unitary EPSC amplitude versus [Ca2+]o were shifted toward higher [Ca2+]o in BoNT/A- or BoNT/C-treated cultures, but their slope was unchanged and the maximal EPSC amplitudes were reduced. We conclude that BoNTs reduce the Ca2+ sensitivity of the exocytotic machinery and the number of quanta released.

Animals↗

[Molecular mechanism of action of tetanus toxin and botulinum neurotoxins].

Tetanus toxin and botulinum neurotoxins are di-chain proteins of 150 kD molecular weight. They are produced by bacteria of the Clostridium genus. These toxins act on the nervous system by inhibiting neurotransmitter release (glycine and GABA in the case of tetanus toxin; acetylcholine in the case of botulinum neurotoxins) thus inducing the spastic or flaccid paralysis that characterizes tetanus and botulism, respectively. Their cellular mechanism of action involves three main steps, namely binding to the neurone membrane, internalization and intracellular blockade of the release mechanism for neurotransmitters. Membrane acceptors for these toxins are not yet fully identified; they would consist of membrane gangliosides and proteins. The internalization step would be achieved by endocytosis. Recent findings show that both binding and internalization are mediated only by the heavy chain of the toxins whereas the intracellular blockade of neurotransmitter release involves their light chain alone. The light chain has been identified as a zinc metalloprotease and its substrates would be proteins involved in the neurotransmitter release mechanism. The target of tetanus toxin and of botulinum neurotoxin type B is VAMP/synaptobrevin, a membrane protein of the synaptic vesicles of nerve cell terminals.

Botulinum Toxins↗

Sustained and selective block of IPSPs in brain slices from rats made epileptic by intrahippocampal tetanus toxin.

A small dose of tetanus toxin (2-5 ng; 10 mouse LD50) injected into the rat hippocampus produces a chronic epileptic syndrome in which epileptic discharges recur intermittently for 6-8 weeks. Hippocampal slices prepared during this period and maintained in vitro generate both evoked and spontaneous epileptic discharges. The present study used slices prepared 8-18 days after injection of tetanus toxin or vehicle solution into both hippocampi to test whether or not synaptic inhibition was selectively impaired in this experimental epilepsy. Intracellular recordings were made from CA3 pyramidal layer neurones within the tetanus toxin focus, which was identified by field potential recordings of synchronous bursts evoked by afferent stimulation. The intrinsic properties of these neurones did not differ from comparable cells in control-injected rats. All cells generated excitatory postsynaptic potentials (EPSPs) following stimulation of stratum radiatum in CA3. In control slices EPSPs were followed by a 'fast' inhibitory postsynaptic potential (IPSP), peaking at 25-30 ms, with a mean amplitude (+/- SEM) of -6.7 mV (+/- 0.66). In the epileptic slices these were absent, and the EPSP prolonged so that the potential at 30 ms was a depolarisation of +6.6 mV (+/- 2.75). The slow IPSP at 120 ms dropped to -0.27 mV (+/- 0.18) from -3.97 mV (+/- 1.43) (11 cells in each group). The loss of IPSPs cannot be attributed to a shift in reversal potentials in the toxin-injected group because no IPSPs were unmasked by current injection (n = 11). IPSPs also occurred spontaneously in the neurones in control slices, with a mean amplitude of -1.30 mV. Their frequency decreased by a factor of 13 in cells from the chronic focus induced by tetanus toxin (P less than 0.0001, analysis of variance), but their amplitude did not change significantly (mean of -1.22 mV). Spontaneous EPSPs were significantly more frequent and slightly smaller in the toxin-injected group (mean amplitudes 1.35 and 1.13 mV respectively). Together these studies support the hypothesis that the chronically recurring seizures induced by low doses of tetanus toxin can be attributed to a substantial, persistent and selective reduction of inhibitory neurotransmission in the hippocampus.

Animals↗

A comparison of enzyme immunoassay and bioassay for the quantitative determination of antibodies to tetanus toxin.

Antibodies to tetanus toxin were induced in sheep by hyperimmunization over 24 weeks. Bleeds taken at weeks 4, 8, 20 and 30 were assayed for antibody titre by both an enzyme immunoassay (EIA) using a newly-described urease enzyme/substrate system and by bioassay in mice. There was a very good correlation between the two assay systems and, with the exception of the week 4 Bleeds, the relationship was the same at all stages of hyperimmunization regardless of titre, adjuvant, or whether toxin or toxoid was used as immunogen or for coating the plates. The results establish that the EIA can replace the bioassay for the determination of tetanus antitoxin in ovine sera.

Animals↗

Glutamate transmission is involved in the mechanisms of neuronal degeneration produced by intrahippocampal tetanus toxin in rats.

Tetanus toxin (TT) blocks GABA-mediated inhibitory neurotransmission in the mammalian CNS via selective inhibition of transmitter release. The loss of central inhibition produces an excitatory focus resembling human limbic epilepsy. We now report that the net excitation caused by an unopposed action of glutamic acid may also produce neuronal degeneration in the rat brain. Anaesthetized rats were placed in a stereotaxic frame and TT (1 microliter dissolved in phosphate buffer, pH 7.0) was injected unilaterally into the dorsal hippocampus. Injection of TT (1000 mouse minimum lethal doses, MLDs; n = 3-6 rats per group) produced time-dependent neuronal loss in the CA1 pyramidal cell layer which was significant (p < 0.05) 7 and 10 days, but not 1 day, after the injection. Systemic treatment with competitive (CGP 37849, 3 mg/kg i.p) or non-competitive (MK801, 0.3 mg/kg i.p.) antagonists at the N-methyl D-aspartate (NMDA) receptor complex 1 h before and 1 h after TT and then once daily for 10 days protected rats from the hippocampal damage produced by TT (1000 MLDs). In addition, in rats bearing a monolateral surgical lesion of the Schaffer collaterals, through which CA1 neurones receive a robust excitatory input from CA3 pyramids, the bilateral injection of TT (1000 MLDs/side) produced significant neuronal loss in the unlesioned hippocampus whereas the contralateral appeared to be preserved. In conclusion, these results demonstrate that excitatory neurotransmission may be involved in the neuropathology elicited by intrahippocampal TT in rats.

2-Amino-5-phosphonovalerate↗

Identification of a ganglioside recognition domain of tetanus toxin using a novel ganglioside photoaffinity ligand.

Tetanus toxin entry into vertebrate motorneurons may involve binding of neuronal surface gangliosides containing the "1b" substructure (a NeuAcalpha2,8NeuAc group on an internal galactose residue). The domains of tetanus toxin involved in ganglioside binding are known to reside within the carboxyl-terminal half of the toxin's heavy chain ("C fragment"). We developed a novel photoaffinity reagent based upon the structure of the 1b ganglioside GD1b (125I-azido-GD1b) to define the ganglioside-binding domains of tetanus toxin. Using this ligand, we observed radiolabeling of tetanus toxin C fragment which could be specifically inhibited by a ganglioside of the 1b series (GT1b), but not by a non-1b series ganglioside (GM3). When tetanus toxin C fragment was proteolyzed with clostripain, whether before or after reaction with 125I-azido-GD1b, a radiolabeled band was observed by SDS-polyacrylamide gel electrophoresis autoradiography, which was selectively inhibited by GT1b. Protein sequencing of proteolyzed tetanus toxin C fragment co-migrating with that band revealed the carboxyl-terminal 34 amino acid residues of tetanus toxin. Matrix-assisted laser desorption/ionization mass spectrometry of a photoaffinity labeled synthetic polypeptide representing the 34-amino acid domain revealed modification at a single residue (His1293). We propose that this domain of tetanus toxin is sufficient for ganglioside binding.

Affinity Labels↗