Inter-individual variability in equine antibody responses to African snake venoms follows heavy-tailed distributions with implications for antivenom production

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  Inter-individual variability in equine antibody responses to African snake venoms follows heavy-tailed distributions with implications for antivenom production Abstract Variability in the antibody response of horses used for snake antivenom manufacture is well recognized, yet its statistical structure and implications for industrial productivity remain poorly characterized. In this study, we quantified antivenom antibody titers by ELISA in a cohort of 14 horses immunized with venoms from the clinically most important snakes in sub-Saharan Africa. To integrate antibody levels with plasma availability, we calculated the Cumulative Plasma Productivity (CPP) by converting individual plasma volumes into titer-corrected equivalents and sequentially pooling these volumes according to their corrected contribution. Distributional analysis revealed right-skewed, heavy-tailed patterns better approximated by a log-normal model than by a strict Pareto (power-law) form, with approximately 20–3...

Venomics of the six-eyed sand spider, Sicarius rugosus (Araneae: Sicariidae), from the neotropical dry forest of Costa Rica

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Venomics of the six-eyed sand spider, Sicarius rugosus (Araneae: Sicariidae), from the neotropical dry forest of Costa Rica

Abstract

Background

Sicarius rugosus, the only member of the genus that inhabits Central America, is phylogenetically related to South American Sicarius spiders. These originated from a common ancestor with sister African species. Like Loxosceles, Sicarius exhibits venom phospholipase D activity due to a group of toxins known collectively as SicTox.

Methods

A gel-assisted, bottom-up, proteomic analysis was performed to characterize the venom composition of S. rugosus. Hyaluronidase activity was determined using zymography.

Results

We identified several SicTox sequences, all classified as β-clade paralogs and sharing unique peptides with proteins from S. patagonicus, S. peruensis, and other species. Enzymes such as metalloproteinases, including putative astacins, carboxypeptidases, and angiotensin-converting enzymes, were detected in the venom. We also identified probable serine proteinases and a toxin-processing peptidylglycine α-hydroxylating monooxygenase, which may participate in venom peptide maturation. The venom displays in vitro hyaluronidase activity. Some likely peptide toxins were also identified, including a sicaritoxin, which preferentially targets insects.

Conclusion

This represents the first proteomic study of the rare six-eyed sand spider, S. rugosus, from the dry forest of Costa Rica, confirming the presence of sequences similar to phospholipases D of other Sicarius and Loxosceles species, as well as venom neuropeptides and enzymes characteristic of the family Sicariidae, which may participate in tissue spreading and processing of other venom constituents.

Díaz, C., Bonilla, F., Fernández, J. et al. Venomics of the six-eyed sand spider, Sicarius rugosus (Araneae: Sicariidae), from the neotropical dry forest of Costa Rica. JoBAZ 87, 40 (2026). https://doi.org/10.1186/s41936-026-00579-1