Integrative transcriptomic, proteomic, biochemical and neutralization studies on the venom of Micrurus ephippifer

Species of the genus Micrurus belong to the family Elapidae and possess venoms of significant clinical importance. This study presents an analysis of the venom composition of Micrurus ephippifer, employing transcriptomic and proteomic methodologies. A total of 2885 venom gland transcripts were assembled, of which 42 were identified as toxins. Transcripts for three-finger toxins (3FTx) were the most abundant (80.7 %), followed by PLA₂ transcripts (16.3 %). Tryptic peptide sequences obtained through bottom-up shotgun MS/MS venom analysis were assigned to 46 distinct proteins in the SwissProt/UniProt database, of which 23 belong to the 3FTx family. Peptide spectral matching against the venom gland transcriptome database identified 24 proteins, 12 of which correspond to 3FTx, and three belong to PLA₂. Venom decomplexation by RP-HPLC followed by N-terminal amino acid sequencing of fractions allowed an estimation of the relative abundance of protein families, indicating that 3FTx comprise over 50 % of the venom. The identified toxic fractions displayed distinct lethality profiles in mice, with certain combinations exhibiting enhanced toxicity, very similar to what has been reported with Brownitoxin-I, with only the PLA2 sequence showing similarity. Our results emphasize the importance of integrating transcriptomic and proteomic approaches to understand venom diversity and its implications for antivenom development.
Significance: Mexico ranks first in the Americas in snake venom diversity. Paradoxically, very little is known about the composition of coral snake venoms, and Micrurus ephippifer is a clear example of this gap, as nothing was known about its venom composition. This type of study provides valuable information that helps fill these knowledge gaps. This study presents the second report of coral snake venoms containing a complex of phospholipase A2 and a three-finger toxin, offering important data that, with further research, will contribute to understanding venom evolution and evaluating the efficacy of antivenoms.