Enzyme-linked immunosorbent assay (ELISA) for the detection and differentiation of Clostridium botulinum toxins type A and B.

Affinity chromatography has been used for a two-step purification of commercial horse botulinum antitoxic globulins type A and B. The first step performed using CH-Sepharose 4B conjugated to toxin type A (or B), permitted the removal of non-botulinal antibodies from antitoxic globulin type A (or B). The anti-botulinal antibodies obtained from the first step were cross-absorbed in the second affinity chromatography using CH-Sepharose 4B conjugated to toxin B (for the purification of antibodies to type A) or to toxin A (for antibodies to type B). The antibodies obtained were used to coat polystyrene wells in an ELISA for the detection of botulinum toxin type A and type B. The first purification step increases the sensitivity of such an ELISA whereas the second step improved the specificity of the test. Only slight cross-reactions were observed between the type A and type B detection systems. The sensitivity achieved with ELISA was 100 and 300 DLM (dosis lethalis minima) for type A and B respectively.