Immunological properties of Hn-33 purified from type A Clostridium botulinum

Type A botulinum neurotoxin is produced along with 6-7 neurotoxin associated proteins to form a complex in addition to the neurotoxin. Immunological reactivity of type A botulinum complex and purified hemagglutinin (Fu et al., 1998) to polyclonal antibody raised against the complex have been investigated using ELISA. In competitive ELISA, 50% inhibition of the binding of IgG antibody against complex A is observed at 78 ng/ml of complex and hemagglutinin-33, suggesting that the hemagglutinin-33 accounts for most of the immunogenic response of the complex. Considering the fact that the complex consists of a group of proteins with a cumulative molecular weight of 900 kDa, hemagglutinin-33 may be one of the major immunoreactive proteins present in the type A neurotoxin complex.