RESUMEN
Envenomation by Loxosceles species (brown spider) can lead to local dermonecrosis and to serious systemic effects. The main toxic component in the venom of these spiders is sphingomyelinase D (SMase D) and various isoforms of this toxin are present in Loxosceles venoms. We have produced a new anti-loxoscelic serum by immunizing horses with recombinant SMase D. In the present study, we compared the neutralization efficacy of the new anti-loxoscelic serum and anti-arachnidic serum (the latter serum is used for therapy for loxoscelism in Brazil) against the toxic effects of venoms from spiders of the genus Loxosceles. Neutralization tests showed that anti-SMase D serum has a higher activity against toxic effects of L. intermedia and L. laeta venoms and similar or slightly weaker activity against toxic effects of L. gaucho than that of Arachnidic serum. These results demonstrate that recombinant SMase D can replace venom for anti-venom production and therapy.
Asunto(s)
Antivenenos/farmacología , Hidrolasas Diéster Fosfóricas/inmunología , Picaduras de Arañas/terapia , Venenos de Araña/antagonistas & inhibidores , Animales , Células Cultivadas , Reacciones Cruzadas , Ensayo de Inmunoadsorción Enzimática , Eritrocitos/efectos de los fármacos , Caballos , Humanos , Inmunoquímica , Pruebas de Neutralización , Hidrolasas Diéster Fosfóricas/metabolismo , Conejos , Proteínas Recombinantes/antagonistas & inhibidores , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/metabolismo , Venenos de Araña/enzimología , Venenos de Araña/inmunología , Arañas/enzimología , Arañas/metabolismoRESUMEN
Envenomation by arachnids of the genus Loxosceles can induce a variety of biological effects, including dermonecrosis and hemolysis. We have previously identified in L. intermedia venom two highly homologous proteins with sphingomyelinase activity, termed P1 and P2, responsible for all these pathological events, and also an inactive isoform P3. The toxins P1 and P2 displayed 85% identity with each other at the amino acid level and showed a 57% identity with SMase I, an active toxin from L. laeta venom. Circular dichroism was used to determine and compare the solution structure of the active and inactive isoforms. Effects of pH and temperature change on the CD spectra of the toxins were investigated and correlated with the biological activities. This study sheds new light on the structure-function relationship of homologous proteins with distinct biological properties and represents the first report on the structure-function relationship of Loxosceles sphingomyelinases D.