“…Past research has revealed that subtypes of one serotype can have distinct characteristics. BoNT/A subtypes differ in neuronal cell entry, enzymatic activity of the LC, intracellular trafficking, and potency [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. The gene encoding BoNT/A4 is localized on a plasmid that also carries the gene encoding BoNT/B in the bivalent toxin producing Clostridium botulinum strain 657, showing the potential diverse genetic organization of these potent pathogens [ 30 ].…”