 Currently, there are no licensed vaccines or pre-exposure prophylactic medical countermeasures available to provide protection against botulism. The rBV AB is under development to provide protection of adults 18 to 55 years of age from fatal botulism caused by inhalational intoxication with botulinum neurotoxin complex BoNT serotype A, subtype A1 BoNTA1 and botulinum neurotoxin complex serotype B, subtype B1 BoNTB1. Volunteers will not be exposed to botulism. Protective antibody titers will be measured in serum after vaccination. 