Proteomic profile of the venom of three dark-colored Tityus (Scorpiones: Buthidae) from the tropical rainforests of Costa Rica.

OBJECTIVE: We aimed to elucidate the potential differences in the venom peptide sequences of three Tityus species from Costa Rican rainforests: T. jaimei, T. championi and T. dedoslargos, compared to T. cf. asthenes from Colombia, which could explain the low level of scorpionism in Costa Rica, evidenced by the lack of epidemiological data. METHODOLOGY: We applied venom proteomics of peptides purified by RP-HPLC and compared the obtained sequences from venoms of these Tityus species to the sequences previously identified from Tityus inhabiting other Central and South American regions. RESULTS: Venom proteome analysis evidences that most of the putative peptide toxins identified in Costa Rican dark-colored Tityus are very similar to those present in other T. (Atreus) from the region. CONCLUSIONS: Our study suggests that, in the case of potential envenomation by Tityus in Costa Rica, the same level of toxicity should be observed, compared to other cases caused by members of the subgenus from other geographical localities. On the other hand, compared to countries with more accelerated urban expansion, Costa Rican Tityus still inhabit secondary rainforests and do not commonly share the same spaces with humans, so the lack of epidemiological evidence of medical emergencies caused by envenoming by this scorpion group could be more related to ecological and demographic factors and less attributed to the characteristics of the venom.

Expanding the neutralization scope of the Central American antivenom (PoliVal-ICP) to include the venom of Crotalus durissus pifanorum.

The proteomic, enzymatic, toxicological, and immunogenic profiles of the venom of C. d. pifanorum were studied. It was found that venom of C. d. pifanorum is composed of 63% phospholipases A2 (PLA2s), 13% serine proteinases (SVSPs), 8% bradykinin-potentiating peptides (BPPs), 4% L-amino acid oxidases (LAAOs), 3% metalloproteinases (SVMPs), and other minor components. This composition allows the venom to exert lethal, PLA2, myotoxic, coagulant and defibrinogenating activities, but no azocaseinolytic or hemorrhagic activities. The addition of C. d. pifanorum venom to the group of venoms used as immunogens to produce the Central American antivenom PoliVal-ICP (i.e., venoms of Bothrops asper, Crotalus simus and Lachesis stenophrys) resulted in 1) the expansion of the neutralization scope of the antivenom to cover the venom of C. d. pifanorum and other antigenically related venom (i.e., C. s. scutulatus venom), 2) improvement of the neutralizing potency towards the venom of C. simus, and 3) no significant reduction of the neutralization of venoms of B. asper and L. stenophrys. It was concluded that supplementation of the immunogens used to produce PoliVal-ICP with the venom of C. d. pifanorum is a viable alternative to expand the neutralization scope of the antivenom. BIOLOGICAL SIGNIFICANCE: The venom of Crotalus durissus pifanorum from Venezuela has a proteomic profile like those of other subspecies of the South American rattlesnake C. durissus, with predominance of phospholipases A2 (especially crotoxin) and serine proteinases. This explains a toxicological profile characterized by neurotoxicity, myotoxicity, and coagulopathies, but being devoid of hemorrhagic activity. The antivenom used in Central America (PoliVal-ICP) includes the venom of C. simus, which has a different composition, in the immunizing strategy. Accordingly, this antivenom does not neutralize C. d. pifanorum venom. The addition of C. d. pifanorum venom to the immunizing mixture of PoliVal-ICP expands the neutralizing scope of this antivenom, to cover additional rattlesnake venoms, while not affecting the response to C. simus, Bothrops asper and Lachesis stenophrys venoms. This represents an improvement of the current PoliVal-ICP.