Venomics of the Anchor Coral Snake Micrurus ancoralis: Composition, Toxicological Profile, and Neutralization by Commercial Antivenom.

Coral snakes of the American continent are classified into two genera, Micruroides and Micrurus, with as many as 91 species recognized in the latter. Although envenomings caused by Micrurus are rare, they can be life-threatening due to neurotoxic effects leading to flaccid paralysis and potential respiratory failure. Micrurus ancoralis is found in the Pacific lowlands and along the western slope of the cordillera occidental Cordillera in Colombia. Although this species is relatively common within its distribution range, its phylogenetic position and the characterization of its venom have not been investigated. The results of phylogenetic analysis placed M. ancoralis within the triadal/bicolor clade of species with the characteristic triad pattern and group bicolor. Proteomic characterization of the venom showed predominance of phospholipase A2 (PLA2) enzymes in its composition, with 51.7% of the total protein content, followed by three-finger toxins (3FTxs; 23.2%) and lower proportions of proteins belonging to several other minor families. Out of 28 chromatographic venom fractions obtained, the seven most abundant were evaluated for toxicity, with three of them (F7, identified as a 3FTx, and F18 and F20 (both identified as PLA2s)) showing lethal activity by the intraperitoneal route in mice. The PLA2 activity of F20 was confirmed and its edema-inducing, myotoxic, and lethal effects in mice were demonstrated. A therapeutic equine anti-coral antivenom (INS, Colombia) against coral snake envenomings immunorecognized the whole venom and its fractions in ELISA tests and was able to neutralize 2 × LD50 (medial lethal dose) of M. ancoralis venom by preincubation, with an estimated potency of at least 0.2 mg venom/mL antivenom. This result suggests that envenomings by M. ancoralis could be effectively treated by this antivenom.