Development of sensitive colorimetric capture elisas for Clostridium botulinum neurotoxin serotypes A and B

Sensitive and specific enzyme-linked immunosorbent assays were developed to detect Clostridium botulinum neurotoxin serotypes A (BoNT A) and B (BoNT B ) in assay buffer and human serum. The assay is based upon affinity-purifie d horse polyclonal antibodies directed against the similar to 50 kDa C-frag ments of each toxin. Standard curves were linear over the range of 0.1-10 n g/mL. Detection was possible at 0.2 ng/mL (20 pg/well) and accurate quantit ation at 0.5 ng/mL (50 pg/well) in assay buffer and 10% human serum. Variat ions between triplicates was typically 5-10%. Less than 1% cross reactivity occurred between other serotypes when each assay was performed against ser otypes A, B and E. When tested against toxins complexed to their associated nontoxic proteins, interference was absent (BoNT B) or <25% (BoNT A). Thes e assays demonstrate sensitivity close to that of the mouse bioassay withou t the use of animals and in a much simpler format than other reported assay s of similar sensitivity. Published by Elsevier Science Ltd.