Toxicity of the venom of Latrodectus (Araneae: Theridiidae) spiders from different regions of Argentina and neutralization by therapeutic antivenoms.

"Black widow" spiders belong to the genus Latrodectus and are one of the few spiders in the world whose bite can cause severe envenomation in humans and domestic animals. In Argentina, these spiders are distributed throughout the country and are responsible for the highest number of bites by spiders of toxicological sanitary interest. Here, we studied the toxicity and some biochemical and immunochemical characteristics of eighteen venom samples from Latrodectus spiders from eight different provinces of Argentina, and the neutralization of some of these samples by two therapeutic antivenoms used in the country for the treatment of envenomation and by a anti-Latrodectus antivenom prepared against the venom of Latrodectus mactans from Mexico. We observed important toxicity in all the samples studied and a variation in the toxicity of samples, even in those from the same region and province and even in the same Latrodectus species from the same region. The therapeutic antivenoms efficiently neutralized all the venoms studied.

Use of an enzyme-linked immunosorbent assay that utilizes the Tc13Tul antigen of Trypanosoma cruzi to monitor patients after treatment with benznidazole.

Tc13Tul antigen is expressed in the mammalian stages of Trypanosoma cruzi, the etiological agent of Chagas' disease. Here, we designed and validated an enzyme-linked immunosorbent assay using the recombinant Tc13Tul (Tc13Tul-ELISA) and found that it had 82.5% sensitivity and 97.05% of specificity. To evaluate whether the decrease in antibodies against Tc13Tul may be used as an early marker of the effect of chemotherapy with benznidazole, sera from 30 T. cruzi-infected children were evaluated by Tc13Tul-ELISA before and after benznidazole treatment. While in Group A (6 months-4 years old, n = 16) the decrease of more than 30% of Tc13Tul-ELISA values showed a sensitivity similar to that of conventional serology (CS); in Group B, (5-12 years old, n = 14) the decrease of Tc13Tul-ELISA values was a better parameter than negativization of CS to monitor the impact of treatment. Therefore, the dosage of anti-Tc13Tul antibodies may be useful as a methodology complementary to CS to evaluate chagasic patients undergoing chemotherapy with benznidazole.