Micrurus snake venoms activate human complement system and generate anaphylatoxins

In the present study we have investigated the action of venoms from seven species of snakes from the genus Micrurus on the complement system in in vitro studies. Several of the Micrurus species could consume the classical and/or the lectin pathways, but not the alternative pathway, and C3a, C4a and C5a were generated in sera treated with the venoms as result of this complement activation. Micrurus venoms were also able to directly cleave the α chain of the component C3, but not of the C4, which was inhibited by 1,10 Phenanthroline, suggesting the presence of a C3α chain specific metalloprotease in Micrurus spp venoms. Furthermore, complement activation was in part associated with the cleavage of C1-Inhibitor by protease(s) present in the venoms, which disrupts complement activation control.Micrurus venoms can activate the complement system, generating a significant amount of anaphylatoxins, which may assist due to their vasodilatory effects, to enhance the spreading of other venom components during the envenomation process.The Elapidae family is represented in America by three genera of coral snakes: Micruroides, Leptomicrurus and Micrurus, the latter being the most abundant and diverse group. In Brazil, M. corallinus and M. frontalis are responsible for the majority of coral snake envenomations. Although, Micrurus bites are relatively rare, the accidents can cause death, by muscle paralysis and respiratory arrest, few hours after envenomation [1].The main feature of the coral snake action is the neurotoxicity, although, experimentally, it has been documented that some Micrurus venoms may produce myotoxicity and local lesions [2,3]. Furthermore, many enzymatic activities were detected in Micrurus venoms including phospholipase A2, hyaluronidase, phosphodiesterase, leucine amino peptidase, L-amino acid dehydrogenase and L-amino acid oxidase activities [4-6]. Only little or no proteolytic effects have been detected in Micrurus venoms [5,6].Previously, we have analyzed