Exceptionally potent human monoclonal antibodies are effective for prophylaxis and treatment of tetanus in mice
Marco Pirazzini, Alessandro Grinzato, Davide Corti, Sonia Barbieri, Oneda Leka, Francesca Vallese, Marika Tonellato, Chiara Silacci-Fregni, Luca Piccoli, Eaazhisai Kandiah, Giampietro Schiavo, Giuseppe Zanotti, Antonio Lanzavecchia, Cesare Montecucco
Marco Pirazzini, Alessandro Grinzato, Davide Corti, Sonia Barbieri, Oneda Leka, Francesca Vallese, Marika Tonellato, Chiara Silacci-Fregni, Luca Piccoli, Eaazhisai Kandiah, Giampietro Schiavo, Giuseppe Zanotti, Antonio Lanzavecchia, Cesare Montecucco
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Research Article Neuroscience

Exceptionally potent human monoclonal antibodies are effective for prophylaxis and treatment of tetanus in mice

Abstract

We used human monoclonal antibodies (humAbs) to study the mechanism of neuron intoxication by tetanus neurotoxin and to evaluate these antibodies as a safe preventive and therapeutic substitute for hyperimmune sera to treat tetanus in mice. By screening memory B cells from immune donors, we selected 2 tetanus neurotoxin–specific mAbs with exceptionally high neutralizing activities and extensively characterized them both structurally and functionally. We found that these antibodies interfered with the binding and translocation of the neurotoxin into neurons by interacting with 2 epitopes, whose identification pinpoints crucial events in the cellular pathogenesis of tetanus. Our observations explain the neutralization ability of these antibodies, which we found to be exceptionally potent in preventing experimental tetanus when injected into mice long before the toxin. Moreover, their Fab derivatives neutralized tetanus neurotoxin in post-exposure experiments, suggesting their potential for therapeutic use via intrathecal injection. As such, we believe these humAbs, as well as their Fab derivatives, meet the requirements to be considered for prophylactic and therapeutic use in human tetanus and are ready for clinical trials.

Authors

Marco Pirazzini, Alessandro Grinzato, Davide Corti, Sonia Barbieri, Oneda Leka, Francesca Vallese, Marika Tonellato, Chiara Silacci-Fregni, Luca Piccoli, Eaazhisai Kandiah, Giampietro Schiavo, Giuseppe Zanotti, Antonio Lanzavecchia, Cesare Montecucco

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Figure 7

TT104 and TT110 humAbs allow long-lasting prophylactic protection against TeNT, and their Fab derivatives prevent tetanus development after toxin challenge.

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TT104 and TT110 humAbs allow long-lasting prophylactic protection agains...
(A) Time course for testing the prophylactic activity of humAbs. Mice were i.p. preinjected with either TT104 (400 ng/kg) or TT110 (400 ng/kg) or their combination (200 ng/kg plus 200 ng/kg), or with TIG (3.5 IU/kg roughly corresponding to 250 IU/70 kg) for 15 or 7 days. TeNT (4 ng/kg) was then inoculated i.p., and the animals were observed for 200 hours for tetanus symptoms. (B and C) Prophylactic profiles for TT104 (B) and TT110 (C) injected alone. (D) Survival curves for mice treated with TT104 plus TT110 in combination compared with TIG. (E) Time course for testing TeNT neutralization by Fabs in a post-exposure challenge. TeNT (4 ng/kg) was delivered via i.p. injection. At the indicated time points, the combination of TT104 and TT110 Fab derivatives (1.2 μg/kg) or TIG (7 IU/kg) was injected i.p., and the animals were observed for 200 hours. (F) Survival plot for mice injected with TeNT and treated with either TT104 plus TT110 Fab derivatives (1.2 μg/kg, orange traces) or TIG (7 IU/kg, cyan traces) after 6 or 12 hours. Statistical significance was calculated with a Mantel-Cox test. The number of mice in each group is indicated in the panel. B, C, D, and F display the same lethality curve for the saline group, as this curve was derived from the data for all the mice treated with TeNT alone, plotted together.