Diversity of Micrurus Snake Species Related to Their Venom Toxic Effects and the Prospective of Antivenom Neutralization

The Elapidae family is represented in America by three genera of coral snakes: Micruroides, Leptomicrurus and Micrurus, the latter being the most abundant and diversified group. Micrurus bites can cause death by muscle paralysis and respiratory arrest few hours after envenomation. The specific treatment for Micrurus envenomation is the application of heterologous antivenom. The aim of this study was to compare the toxicity of venoms from nine species of coral snakes and analyze the neutralization potential of the Brazilian coral snake antivenom. In vitro assays showed that the majority of the Micrurus venoms are endowed with phospholipase and hyaluronidase and low proteolytic activities. These enzymes are not equally neutralized in all venoms by the therapeutic antivenom. Moreover, in vivo assays showed that some of the Micrurus venoms are extremely lethal, such as the ones from M. altirostris, M. corallinus, M. frontalis, M. lemniscatus and M. spixii. Neutralization tests, performed in vivo, showed that the therapeutic antivenom was able to neutralize better the venoms from M. frontalis, M. corallinus, and M. spixii but not from M. altirostris and M. lemniscatus. Taken together, these results suggest that modifications in the immunization antigenic mixture should occur in order to generate more comprehensive therapeutic antivenom

Micrurus snake venoms activate human complement system and generate anaphylatoxins

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. Conclusion 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

Some aspects of the venom proteome of the Colubridae snake Philodryas olfersii revealed from a Duvernoy’s (venom) gland transcriptome

AbstractWe investigated the putative toxins of Philodryas olfersii (Colubridae), a representative of a family of snakes neglected in venom studies despite their growing medical importance. Transcriptomic data of the venom gland complemented by proteomic analysis of the gland secretion revealed the presence of major toxin classes from the Viperidae family, including serine proteases, metalloproteases, C-type lectins, Crisps, and a C-type natriuretic peptide (CNP). Interestingly, the phylogenetic analysis of the CNP precursor showed it as a linker between two related precursors found in Viperidae and Elapidae snakes. We suggest that these precursors constitute a monophyletic group derived from the vertebrate CNPs

Summary of the biological activities of <i>Micrurus</i> spp venoms, cross-reactivity and neutralization potential of the Brazilian coral snake antivenom.

<p><b>PLA₂:</b> Phospholipase A₂; <b>P:</b> Protease; <b>H:</b> Hyaluronidase;</p><p>High (+++); Intermediate (++); Low (+); Very low (+/−); Absent: (−); not determined (nd).</p

Determination of the phospholipase A₂ activity.

<p>Samples of individual <i>Micrurus</i> venoms (4 µg), or a mixture of <i>M. frontalis</i> (2 µg) and <i>M. corallinus</i> (2 µg), venoms were incubated for 20 min at 37°C with 180 µL of a mixture containing 5 mM Triton X-100, 5 mM phosphatidylcholine, 2 mM HEPES, 10 mM calcium chloride and 0.124% (wt./vol) bromothymol blue dye in water. Results are representative for three separate experiments and expressed as nanomoles acid <i>per</i> minute <i>per</i> µg of venom.</p