| Summary: | <p>Abstract</p> <p>Background</p> <p>The genus <it>Micrurus</it>, coral snakes (Serpentes, Elapidae), comprises more than 120 species and subspecies distributed from the south United States to the south of South America. <it>Micrurus </it>snake bites can cause death by muscle paralysis and further respiratory arrest within a few hours after envenomation. Clinical observations show mainly neurotoxic symptoms, although other biological activities have also been experimentally observed, including cardiotoxicity, hemolysis, edema and myotoxicity.</p> <p>Results</p> <p>In the present study we have investigated the action of venoms from seven species of snakes from the genus <it>Micrurus </it>on the complement system in <it>in vitro </it>studies. Several of the <it>Micrurus </it>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. <it>Micrurus </it>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 <it>Micrurus </it>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.</p> <p>Conclusion</p> <p><it>Micrurus </it>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.</p>
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