Atheris Laboratories (Switzerland)

Venomous animal envenomation remains a significant but neglected public health problem worldwide, with an estimated 5.4 million cases and up to 138,000 deaths annually. The burden is particularly acute in tropical and subtropical regions, especially sub-Saharan Africa, where rural and vulnerable populations face limited access to effective antivenoms and healthcare. Despite this, comprehensive data on envenomation incidence, clinical management, and outcomes remain scarce, hampering efforts to develop effective prevention and treatment strategies. This review synthesizes current knowledge on venomous animal diversity, epidemiology, and clinical manifestations globally, with a focus on Africa’s unique challenges. We examine critical gaps in antivenom production, distribution, and affordability, and highlight international initiatives, including the World Health Organization’s 2019 roadmap for snakebite envenoming control. Recent advances in diagnostics, therapeutics, and community engagement are discussed alongside persistent barriers to implementation. Finally, we propose strategic recommendations to strengthen surveillance, improve antivenom accessibility, and foster regional collaborations to reduce envenomation morbidity and mortality in Africa. Addressing these challenges requires coordinated global and local efforts to translate scientific advances into sustainable health outcomes for affected populations.

Venoms contain active substances with highly specific physiological effects and are increasingly being used as sources of novel diagnostic, research and treatment tools for human disease. Experimental characterisation of individual toxin activities is a severe rate-limiting step in the discovery process, and in-silico tools which allow function to be predicted from sequence information are essential. Toxins are typically members of large multifunctional families of structurally similar proteins that can have different biological activities, and minor sequence divergence can have significant consequences. Thus, existing predictive tools tend to have low accuracy. We investigated a classification model based on physico-chemical attributes that can easily be calculated from amino-acid sequences, using over 250 (mostly novel) viperid phospholipase A2 toxins. We also clustered proteins by sequence profiles, and carried out in-vitro tests for four major activities on a selection of isolated novel toxins, or crude venoms known to contain them. The majority of detected activities were consistent with predictions, in contrast to poor performance of a number of tested existing predictive methods. Our results provide a framework for comparison of active sites among different functional sub-groups of toxins that will allow a more targeted approach for identification of potential drug leads in the future.

Animal venoms represent a rich resource of bioactive molecules. These complex biofluids contain a multitude of proteins, peptides and small molecules that act with high specificity and potency on numerous physiological processes, such as ion channels and receptors. In this regard, spiders are no exception, and several molecules of biomedical interest have already been identified and characterized in their venoms. Furthermore, analysis of their haemolymph has revealed numerous antimicrobial peptides, the silk they produce is also of interest and insect-selective toxins are developed as insecticides. However, compared with snakes, scorpions and marine organisms, obtaining adequate amounts of spider venom requires a substantial effort. As a consequence, spider venoms have been relatively poorly investigated. Indeed, until now, the main focus has been on large theraphosid spiders and species with life-threatening venom, thus covering only the tip of the iceberg of the huge molecular biodiversity offered by arachnids. Nonetheless, recent technological and strategic developments that enable the discovery of new bioactive ingredients in small amounts of raw material have paved the way to novel discoveries in spider venom. The aim of this chapter is to highlight the interest of spider venom for the pharmaceutical and biotechnology industries.

Conopeptides are toxins expressed in the venom duct of cone snails (Conoidea, Conus). These are mostly well-structured peptides and mini-proteins with high potency and selectivity for a broad range of cellular targets. In view of these properties, they are widely used as pharmacological tools and many are candidates for innovative drugs. The conopeptides are primarily classified into superfamilies according to their peptide signal sequence, a classification that is thought to reflect the evolution of the multigenic system. However, this hypothesis has never been thoroughly tested. Here we present a phylogenetic analysis of 1,364 conopeptide signal sequences extracted from GenBank. The results validate the current conopeptide superfamily classification, but also reveal several important new features. The so-called "cysteine-poor" conopeptides are revealed to be closely related to "cysteine-rich" conopeptides; with some of them sharing very similar signal sequences, suggesting that a distinction based on cysteine content and configuration is not phylogenetically relevant and does not reflect the evolutionary history of conopeptides. A given cysteine pattern or pharmacological activity can be found across different superfamilies. Furthermore, a few conopeptides from GenBank do not cluster in any of the known superfamilies, and could represent yet-undefined superfamilies. A clear phylogenetically based classification should help to disentangle the diversity of conopeptides, and could also serve as a rationale to understand the evolution of the toxins in the numerous other species of conoideans and venomous animals at large.

Gomesin is an antimicrobial peptide isolated from hemocytes of the Brazilian spider Acanthoscurria gomesiana that contains two disulfide bridges Cys(2-15)/Cys(6-11) and presents a beta-hairpin structure. To investigate the role of the disulfide bridges on gomesin conformation, bioactivities, and serum stability, structure-activity relationship (SAR) studies were conducted. Initially, gomesin and variants lacking one or both disulfide bridges were synthesized. CD studies showed that the gomesin structure is very rigid independently of the solvent environment. On the other hand, the linearized analogues adopted secondary structures according to the environment, while the monocyclic disulfide-bridged peptides had a tendency to adopt a turn structure. The absence of one or both bridges resulted in a decrease in the antimicrobial and hemolytic activities. In addition, serum stability studies revealed that, contrasting to gomesin that was stable even after 48 h of incubation, the linearized analogues were rapidly degraded. The replacement of the disulfide bounds by lactam bridges led to monocyclic and bicyclic compounds. SAR studies indicated that the monocyclic lactam-bridged analogues tend to assume a alpha-helical structure being less potent, hemolytic, and serum stable than the wild-type gomesin. On the other hand, the bicyclic lactam/disulfide-bridged analogues displayed a similar conformation and degradation kinetics identical to gomesin. However, the antimicrobial activity appeared to be dependent on the lactam bridge position and size. These findings indicated that (i) the secondary structure plays a pivotal role for the full activity of gomesin; (ii) the antimicrobial and hemolytic activities of gomesin are correlated events; (iii) while at least one of the disulfide bridges is needed for the maintenance of a significant antimicrobial activity of gomesin, both bridges are required for high serum stability and optimal conformation; and finally (iv) the best analogue obtained was the bicyclo (2-15,6-11)[Glu2, Cys(6,11), Lys15]-Gm since it is as stable and potent as gomesin.

How close are we to using proteomics tools in the every day practice of physicians? What are the socio-economical issues our health care system may face with the advent of biomarkers for early diagnosis? How to get the specialists from the various disciplines integrated in proteomics to establish a common understanding of the clinical issues and develop the necessary standards (methods, biochemicals and IT)? These were the kind of questions a panel of specialists tried to answer during the roundtable discussion that took place in Bern during the Swiss Proteomics Society 2004 congress.

The nature of secreted aminopeptidases in Trichophyton rubrum was investigated by using a reverse genetic approach. T. rubrum genomic and cDNA libraries were screened with Aspergillus spp. and Saccharomyces cerevisiae aminopeptidase genes as the probes. Two leucine aminopeptidases, ruLap1 and ruLap2, and two dipeptidyl-peptidases, ruDppIV and ruDppV, were characterized and compared to orthologues secreted by Aspergillus fumigatus using a recombinant protein from Pichia pastoris. RuLap1 is a 33 kDa nonglycosylated protein, while ruLap2 is a 58-65 kDa glycoprotein. The hydrolytic activity of ruLap1, ruLap2 and A. fumigatus orthologues showed various preferences for different aminoacyl-7-amido-4-methylcoumarin substrates, and various sensitivities to inhibitors and cations. ruDppIV and ruDppV showed similar activities to A. fumigatus orthologues. In addition to endopeptidases, the four aminopeptidases ruLap1, ruLap2, ruDppIV and ruDppV were produced by T. rubrum in a medium containing keratin as the sole nitrogen source. Synergism between endo- and exopeptidases is likely to be essential for dermatophyte virulence, since these fungi grow only in keratinized tissues.