Full characterization of three toxins from the Androctonus amoreuxi scorpion venom

Abstract

In this study, we have characterized the immunological and pharmacological properties of the three major α-type toxins from the scorpion Androctonus amoreuxi, AamH1, AamH2 and AamH3, which were previously described as putative toxins from cDNAs [Chen, T. et al., 2003. Regul. Pept. 115, 115–121]. The immunological tests (ELISA, RIA) have demonstrated that AamH1, AamH2 and AamH3 belong to the immunological groups 3 and 4 of α-type toxins. Analysis of the three toxin effects on currents through rat brain (rNav1.2), rat muscle (rNav1.4) and Drosophila (DmNav1) sodium channels expressed in Xenopus oocytes revealed that AamH1 and AamH2, but not AamH3, have anti-insect and anti-mammal activities and can be classified as α-like toxins. While AamH1 removes fast inactivation only in neuronal rNav1.2 channel and has no effect on muscular rNav1.4 channel, AamH2 affects both neuronal rNav1.2 and muscular rNav1.4 channels. AamH3 was lethal to mice by intracerebroventricular injection despite its lack of activity on the neuronal rNav1.2 channel. Finally, we have shown that the A. amoreuxi venom was better neutralized by the antiserum raised against the venom of Buthus occitanus tunetanus than by the antisera raised against scorpion venoms from the same genus Androctonus.