La sérothérapie antivenimeuse : ses applications, ses limites, son avenir

Un siècle après sa découverte, les auteurs font une mise au point sur la sérothérapie antivenimeuse. Quelques remarques sur les besoins en sérum antivenimeux selon les régions géographiques précèdent une revue des principes de fabrication. La sérothérapie est présentée comme un traitement de grande valeur si l'on respecte les indications, la posologie et la voie d'administration. Quelques orientations nouvelles dans la modernisation de ce produit trop souvent décrié, doivent permettre d'en augmenter l'efficacité et l'innocuité. (Résumé d'auteur

Reappraisal of Vipera aspis Venom Neurotoxicity

BACKGROUND: The variation of venom composition with geography is an important aspect of intraspecific variability in the Vipera genus, although causes of this variability remain unclear. The diversity of snake venom is important both for our understanding of venomous snake evolution and for the preparation of relevant antivenoms to treat envenomations. A geographic intraspecific variation in snake venom composition was recently reported for Vipera aspis aspis venom in France. Since 1992, cases of human envenomation after Vipera aspis aspis bites in south-east France involving unexpected neurological signs were regularly reported. The presence of genes encoding PLA(2) neurotoxins in the Vaa snake genome led us to investigate any neurological symptom associated with snake bites in other regions of France and in neighboring countries. In parallel, we used several approaches to characterize the venom PLA(2) composition of the snakes captured in the same areas. [br/] METHODOLOGY/PRINCIPAL FINDINGS: We conducted an epidemiological survey of snake bites in various regions of France. In parallel, we carried out the analysis of the genes and the transcripts encoding venom PLA(2)s. We used SELDI technology to study the diversity of PLA(2) in various venom samples. Neurological signs (mainly cranial nerve disturbances) were reported after snake bites in three regions of France: Languedoc-Roussillon, Midi-Pyrénées and Provence-Alpes-Côte d'Azur. Genomes of Vipera aspis snakes from south-east France were shown to contain ammodytoxin isoforms never described in the genome of Vipera aspis from other French regions. Surprisingly, transcripts encoding venom neurotoxic PLA(2)s were found in snakes of Massif Central region. Accordingly, SELDI analysis of PLA(2) venom composition confirmed the existence of population of neurotoxic Vipera aspis snakes in the west part of the Massif Central mountains. [br/] CONCLUSIONS/SIGNIFICANCE: The association of epidemiological studies to genetic, biochemical and immunochemical analyses of snake venoms allowed a good evaluation of the potential neurotoxicity of snake bites. A correlation was found between the expression of neurological symptoms in humans and the intensity of the cross-reaction of venoms with anti-ammodytoxin antibodies, which is correlated with the level of neurotoxin (vaspin and/or ammodytoxin) expression in the venom. The origin of the two recently identified neurotoxic snake populations is discussed according to venom PLA(2) genome and transcriptome data

Toxines et défensines de scorpions

International audienceThe scorpion venoms possess many neurotoxic peptides which constitute a group of molecular families with a common architecture and a high degree of polymorphism. This architecture is found also in circulating antimicrobial peptides belonging to the defensins family, which are especially structurally related to the blocking potassium channels neurotoxins. The diversification in functions with a unique architectural scheme is discussed taking in account the biophysiological characteristics of the scorpion order.Les venins de scorpion contiennent un grand nombre de neurotoxines peptidiques qui constituent un ensemble de familles molécu­laires à haut degré de polymorphisme, mais qui ont en commun une architecture semblable. Cette architecture se retrouve dans des peptides antibactériens circulants de la famille des défensines, qui s'apparentent tout particulièrement à celle des neurotoxines actives sur les canaux potas­ sium. Cette diversification de fonctions à partir d'un schéma structurel identique est discutée à la lumière des caractéristiques biophysiologiques des scorpions

Scorpion toxins and defensins

International audienceThe scorpion venoms possess many neurotoxic peptides which constitute a group of molecular families with a common architecture and a high degree of polymorphism. This architecture is found also in circulating antimicrobial peptides belonging to the defensins family, which are especially structurally related to the blocking potassium channels neurotoxins. The diversification in functions with a unique architectural scheme is discussed taking in account the biophysiological characteristics of the scorpion order