Recombinant luminal domain of human synaptotagmin II in combination with gangliosides inhibits the toxicity of botulinum neurotoxins in mice

Synaptotagmin II (syt II) is the specific protein receptor of botulinum neurotoxin B (BoNT/B), and the luminal domain of syt II contains toxin-binding sites that have a high affinity for BoNT/B. However, it is not yet clear whether the luminal domain of syt II (syt II-LD) inhibits the toxicity of BoNT/B by interfering with the toxin–receptor interaction. In this study, we characterized the binding of the purified recombinant syt II-LD to BoNT and revealed that the recombinant syt II-LD in vivo could provide protection against BoNT/B intoxication in mice models, and the neutralization effect could be improved by using gangliosides.