Modification and validation of the Endopep-mass spectrometry method for botulinum neurotoxin detection in liver samples with application to samples collected during animal botulism outbreaks

Annica Tevell Åberg,Mikael Hedeland,Ida Karlsson

doi:10.1007/s00216-020-03001-z

Annica Tevell Åberg, Mikael Hedeland + Show 1 more

Open Access

https://doi.org/10.1007/s00216-020-03001-z

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Journal: Analusis	Publication Date: Oct 29, 2020
Citations: 9	License type: open-access

Affiliation: National Veterinary Institute, Uppsala University

Abstract

Botulinum neurotoxins (BoNTs) are the most potent toxins known and they cause the paralytic disease botulism in humans and animals. In order to diagnose botulism, active BoNT must be detected in biological material. Endopep-MS is a sensitive and selective method for serum samples, based on antibody capture, enzymatic cleavage of target peptides, and detection of cleavage products using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). In many cases of animal botulism, serum samples are not available or they do not contain detectable amounts of BoNT and liver sampling is an alternative for postmortem examinations. However, the Endopep-MS method is impaired by the inherent protease activity of liver samples. In the presented study, the Endopep-MS method has been successfully modified and validated for analysis of cattle, horse, and avian liver samples, introducing a combination of a salt washing step and a protease inhibitor cocktail. These modifications resulted in a substantial decrease in interfering signals and increase in BoNT-specific signals. This led to a substantial improvement in sensitivity for especially BoNT-C and C/D which are among the most prominent serotypes for animal botulism. Botulism was diagnosed with the new method in liver samples from dead cattle and birds from outbreaks in Sweden.Graphical

Highlights

The paralytic disease botulism is caused by botulinum neurotoxins (BoNTs) which are produced by anaerobic bacteria, mainly Clostridium botulinum
Human botulism is normally associated with BoNT-A, B, E, and F [6], while horses are susceptible to BoNT-A, B, or C [7]
Botulinum neurotoxins A, B, C, D/C, E, and F complexes were obtained from Metabiologics (Madison, WI, USA) and used at approximately 2.5 MLD50 for BoNT-A, B, E, and F, i.e., 0.071 ng (BoNT-A), 0.28 ng (BoNT-B), 17 ng (BoNT-E), and 0.50 ng (BoNT-F), and approximately 10 MLD50 for BoNT-C, and Modification and validation of the Endopep-mass spectrometry method for botulinum neurotoxin detection in

Summary

Introduction

The paralytic disease botulism is caused by botulinum neurotoxins (BoNTs) which are produced by anaerobic bacteria, mainly Clostridium botulinum. The disease could either develop after the consumption of food or feed containing the preformed toxin, or by so-called toxicoinfection when the bacteria grow and produce the toxin inside the body, e.g., in the intestine (birds, foals, infants) or in a wound (syringe using drug addicts) [6, 7]

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