Botulinum Toxins, Diversity, Mode of Action, Epidemiology of Botulism in France

Abstract

Botulinum toxins (BoNTs) are the most potent toxins and are responsible for botulism, which is a neurological disease in man and animals. Botulism is characterized by flaccid paralysis and inhibition of secretions. BoNTs are produced by distinct clostridial species including Clostridium botulinum that consist in four physiological and genetic groups, atypical strains of C. baratii and C. butyricum . Recently, nonclostridial bacteria have been found to synthesize BoNTs. The particularity of BoNTs is to associate with nontoxic pro- teins to form large-size complexes that are resistant to acidic pH and protease degrada-tion of the digestive tract. BoNTs are divided into 10 types based on neutralization by specific antisera and into more than 40 subtypes according to their sequence variations. All BoNTs retain a common core structure and mode of action, which consists in the inhibition of neurotransmitter release, notably acetylcholine. Human botulism occurs in three main forms: foodborne botulism, botulism by intestinal colonization including infant botulism, and wound botulism. In France, type B foodborne botulism is the most prevalent form, resulting from the traditional consumption of pork products such as home-made cured ham. Albeit less frequent, human botulism is still present in France including diverse types and origins.