title: Micrurus snake venoms activate human complement system and generate anaphylatoxins.
abstract: BACKGROUND
  The genus Micrurus, coral snakes (Serpentes, Elapidae), comprises more than 120 species and subspecies distributed from the south United States to the south of South America. Micrurus 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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Immunochemistry Laboratory, Butantan Institute, Av, Vital Brazil, 1500, São Paulo, 05503-900, Brazil.
authors.forename: Gabriela D
authors.initials: GD
authors.lastname: Tanaka
authors.forename: Giselle
authors.initials: G
authors.lastname: Pidde-Queiroz
authors.forename: Maria
authors.initials: M
authors.lastname: de Fátima D Furtado
authors.forename: Carmen
authors.initials: C
authors.lastname: van den Berg
authors.forename: Denise V
authors.initials: DV
authors.lastname: Tambourgi
mesh_terms: D000706:Anaphylatoxins / Q000096:biosynthesis*; D000818:Animals; D003167:Complement Activation / Q000187:drug effects*; D050718:Complement C1 Inhibitor Protein / Q000302:isolation & purification / Q000378:metabolism; D003176:Complement C3 / Q000378:metabolism; D004546:Elapid Venoms / Q000378:metabolism / Q000494:pharmacology*; D017815:Elapidae / Q000378:metabolism*; D006801:Humans; D059748:Proteolysis / Q000187:drug effects
chemical_list: D000706:Anaphylatoxins; D050718:Complement C1 Inhibitor Protein; D003176:Complement C3; D004546:Elapid Venoms; C016310:cobra venom factor; C053972:micrurus venom