Extremely potent human monoclonal antibodies for the prophylaxis and therapy of Tetanus

Human monoclonal antibodies were used here to study the mechanism of neuron intoxication by tetanus neurotoxin protein toxins and as a safe preventive and therapeutic substitute of hyperimmune sera. By screening memory B cells of immune donors, we selected two monoclonal antibodies specific for tetanus neurotoxin with exceptionally high neutralizing activities, which have been extensively characterized both structurally and functionally. We found that these antibodies interfere with the binding and translocation of the neurotoxin into neurons by interacting with two epitopes, whose definition pinpoints crucial events in the cellular pathogenesis of tetanus. Some mechanistic aspects of tetanus neurotoxin intoxication were revealed, explaining at the same time, the unprecedented neutralization ability of these antibodies. Importantly, these antibodies are exceptionally efficient in preventing experimental tetanus when injected in mice long before the neurotoxin. Moreover, their Fab derivatives neutralize tetanus neurotoxin in post-exposure experiments, suggesting their potential therapeutic use upon intrathecal injection. As such, these human monoclonal antibodies, as well as their Fab derivatives, meet all requirements for being considered for prophylaxis and therapy of human tetanus and are ready for clinical trials.

The effect of haloperidol, aminooxyacetic acid and (-)-nuciferine on prolonging survival time of mice with tetanus

Introduction. Tetanus, also known as lockjaw, is a very dangerous, infectious, acute, usually afebrile disease characterised by muscle spasms. The causative agent of the disease is the bacterium Clostridium tetani. This pathogen produces a specific neurotoxin, termed tetanus toxin, with two components: tetanospasmin and tetanolysin. Light chains of tetanospasmin cleavage synaptobrevin, which in turn prevent release of the inhibitory neurotransmitter GABA into the synaptic cleft. The ?-motor neurons are, therefore, under no inhibitory control, as a result of which they undergo sustained excitatory discharge causing the characteristic motor spasms of tetanus. Materials and Methods. In this research, we attempted to normalise disorders caused by tetanus toxin by using haloperidol (at doses of 4, 5, 6, 7 and 8 mg/kg b.w.), alone and in combination with (-)-nuciferine (at a dose of 5 mg/kg b.w.) or aminooxyacetic acid (at a dose of 20 mg/kg b.w.). Experiments were conducted on albino mice. Experimental tetanus was induced by application of tetanus toxin. Results and Conclusions. Application of haloperidol (alone and in combination with (-)-nuciferine and aminooxyacetic acid) was carried out 24 h following the application of tetanus toxin. It was found that haloperidol, given alone in a dose of 4 mg/kg, prolonged the average survival time of mice with experimental tetanus by 24.35 h compared to the control animals. Additionally, the combination of haloperidol with (-)-nuciferine slightly, but non-significantly, extended survival time , while the combination of haloperidol with aminooxyacetic acid produced the best effect on extension of survival time (mice survived on average 27.74 h longer than control mice).