02273nas a2200253   4500000000100000000000100001008004100002260007000043653002600113653001300139653001600152653001900168653002400187653002200211100001200233700001400245700001200259700001300271700001300284245012200297490000800419520157800427022001402005       2018                            d  c06/2018bSchlütersche Verlagsgesellschaft mbH & Co. KGaHannover10abotulinum neurotoxins10abotulism10adiagnostics10amouse bioassay10areplacement methods10afunctional assays1 aD Stern1 aL v. Berg1 aM Skiba1 aM Dorner1 aB Dorner00aReplacing the mouse bioassay for diagnostics and potency testing of botulinum neurotoxins – progress and challenges0 v1313 aBotulinum neurotoxins (BoNTs) are the most potent toxins known and the  causative agents of the rare but potentially life-threatening disease botulism. The elaborate mode of action of BoNTs at the molecular level, their exquisite specificity  for peripheral motor neurons, and their ability to effectively inhibit neurotransmitter release led to the development of BoNTs into highly valued pharmaceutical products. Both diagnostics of botulism and potency testing of pharmaceutical BoNT preparations still employ the mouse bioassay as “gold standard assay”. This animal experiment can pose a heavy burden on the animal, including a fatal outcome of testing. Additionally, several analytical disadvantages have been  described. Consequently, the development of animal replacement methods is a long pursued goal which has been focused mainly on replacement methods for pharmaceutical potency testing so far. However, fundamentally different requirements and challenges apply for diagnostics of botulism and potency testing of BoNT pharmaceuticals, which necessitates the development of different assays  tailored for each purpose. Here we review the underlying causes for this intricacy which are rooted in both the biological characteristics of the BoNTs as well as  assay specific requirements. We review different functional assays that have been developed to replace the mouse bioassay. Despite significant progress in recent  years, further substantial work is needed to pave the way for a fully validated replacement for the mouse bioassay for botulism diagnostics.  a0005-9366