High-resolution mass spectrometry and enzyme-linked immunosorbent assay for detection of residual botulinum concentrations in a mouse model of botulism.

[BACKGROUND] Botulinum toxin type A is widely used to block acetylcholine release in the treatment of chronic sialorrhea, muscle spasticity, and dystonia. We aim to develop a user-friendly method for detecting cases of medical botulinum toxin poisoning.

[METHODS] The mice poisoning model was established by injecting or gavage with Botulax®, and the poisoning dose and symptoms were observed. The residual levels of toxin in poisoned mice were detected by high-resolution mass spectrometry and sandwich ELISA, respectively.

[RESULTS] Two hours after poisoning, no residual botulinum toxin was found by mass spectrometry (MS) under our specific untargeted workflow and sample preparation conditions, but ELISA detected residual toxin in various tissues of mice. Among them, the muscle tissue had the highest level. There is no noticeable difference in the levels of toxin residues in the same organs of mice, regardless of the route of poisoning. The sandwich ELISA method is user-friendly for detecting medical botulinum toxin poisoning. The presence of toxin residues can be detected in various tissues two hours after exposure, with muscle being the optimal sampling tissue.

[CONCLUSIONS] Our research indicates that under specific sample preparation, chromatographic separation, and untargeted detection conditions, mass spectrometry may not be effective for detecting Botulinum toxin at concentrations below the ng/ml level. The study demonstrates that ELISA is a sensitive and practical alternative for early detection. Positive results can be detected within 2 h of poisoning, especially when taken from muscle tissue.