Extraction and Inhibition of Enzymatic Activity of Botulinum Neurotoxins/A1, /A2, and /A3 by a Panel of Monoclonal Anti-BoNT/A Antibodies
CENTERS FOR DISEASE CONTROL AND PREVENTION ATLANTA GA
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Botulinum neurotoxins BoNTs are extremely potent toxins that are capable of causing death or respiratory failure leading to long-term intensive care. Treatment includes serotype-specific antitoxins, which must be administered early in the course of the intoxication. Rapid determination of human exposure to BoNT is an important public health goal. Previous work in our laboratory focused on the development of Endopep-MS, a mass spectrometry-based endopeptidase method for detecting and differentiating A-G serotypes in buffer and BoNTA, B, E, and F in clinical samples. We have previously reported the effectiveness of antibody-capture to purify and concentrate BoNTs from complex matrices such as clinical samples. Because some antibodies inhibit or neutralize the activity of BoNT, the choice of antibody with which to extract the toxin is critical. In this work, we evaluated a panel of 16 monoclonal anti-BoNTA antibodies mAbs for their ability to inhibit the in vitro activity of BoNTA1, A2, and A3 complex as well as the recombinant light chain of A1. We also evaluated the same antibody panel for the ability to extract BoNTA1, A2, and A3. MAbs differed significantly with respect to their extraction efficiency, their ability to extract BoNTA subtypes, and their inhibitory effect on BoNT catalytic activity. MAbs binding the C-terminal portion of the BoNTA heavy chain were found to have the optimal properties for use in the Endopep-MS assay.