Toxicity And Immunological Reactivity Of Two North American Loxosceles (“Brown Spider”) venoms. 

¹Estévez, J.; ²Dolab, J.A.; ³Ramos-Cerrillo, B.; ³Olvera, A.; ⁴Francisco Paniagua-Solis, J.F.; ¹Magaña, P.; ²Litwin, S.; ⁵Salas, M.; ^5,6Zavaleta, A.; ³Alagón, A.; ²de Roodt, A.R.

1 Instituto Bioclón, México DF, México. 2 Instituto Nacional de Producción de Biológicos A.N.L.I.S. “Dr. Carlos G. Malbrán”, Ministerio de Salud, Buenos Aires, Argentina. 3 Instituto de Biotecnología, Universidad Autónoma de México, Cuernavaca, Morelos, México. 4 Laboratorios Silanes; México DF, México. 5 Laboratorio de Farmacología, Departamento de Bioquímica, Biología Molecular y Farmacología, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Hered, Lima Perú. 6 Instituto de Medicina Tropical Alexander Von Humboldt, Universidad Peruana Cayetano Heredia, Lima Perú.

The bites of Loxosceles spiders may produce severe lesions that occasionally lead to the death. The treatment applied when Loxosceles bite occurs, is generally symptomatic and it display a high variation of therapeutic measures giving as result a variety of diverse clinical responses, making difficult the evaluation of the different treatments adopted. The only specific treatment for the envenomation by Loxosceles seems to be the use of the specific antivenom, as it was established in South America. It was studied the electrophoretic profile of Loxosceles(L.) reclusa and L. boneti venom glands homogenates and its lethal and necrotizing activities in different strains of mice and rabbits. As at present, any therapeutic antivenom for North American Loxosceles bite has been developed for clinical use, we produced experimental Anti – L. boneti and Anti – L. reclusa antivenoms and tested its immunochemical reactivity and neutralizing capacity on mice and rabbits. Immunochemical studies showed cross reactivity among L. boneti, L. reclusa, L. boneti and L. laeta venoms. Antivenoms against South American L. gaucho and L. laeta cross reacted with both North American Loxosceles venom. Experimental anti- L. boneti and anti- L. reclusa antivenoms protected mice in classical preincubation experiments and in rescue assays of the systemic toxicity of the venom. Both antivenoms were able to neutralize the necrosis rabbit skin. It was observed cross neutralization of the lethal and necrotizing activity by both antivenoms against both venoms. The results suggest that both antivenoms or both antivenoms and an antivenom raised with both venoms as immunogens could be useful for the treatment of bites by North American Loxosceles spiders.

Correspondence to: jestevez@bioclon.com.mx