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.

Intraspecific variability of the Central American rattlesnake (Crotalus simus) venom and its usefulness to obtain a representative standard venom.

Snake venoms are mixtures of proteins whose physicochemical features confer them toxicity and immunogenicity. Animals (e.g., horses or sheep) immunized with snake venoms produce antibodies towards the venom proteins. Since these antibodies can neutralize the venom toxicity, they have been used to formulate snake antivenoms. The efficacy of the antivenoms is widely accepted, and standard venoms are expected to be representative of the snake's population that inhabit in the region where the antivenom is intended to be used. The representativeness of a single venom collected from a Crotalus simus snake, and its usefulness as standard venom to produce an antivenom is evaluated. The use of an "average venom" might be as representative of the population intended to be used, as the standard venom composed by many venom samples. Variations in the relative abundance concentration of crotoxin in the C. simus leads to different clinical manifestations, as well as differences in the neutralization efficacy of the antivenoms. A monovalent anti-Cs antivenom was produced from a single venom C. simus specimen, and its efficacy in neutralizing the lethal activity of 30 C. simus snakes was tested. Despite the variations in the relative abundance content of crotoxin found in the proteomes, the monovalent anti-Cs antivenom was successful in neutralize the toxicity caused by the variations on the venom composition of three different snake population used. Interestingly, it seems that the sex is not a key factor in the lethality of the venoms tested. The concept of representative venom mixtures for immunization should be revised for the case of C. simus on the populations found in Costa Rica, since it might use as less as one representative individual whose venom covers the mainly toxic enzymes.