Comparative analysis of venom from two Honduran pitvipers

Kerwin, Samuel R.

samuel.kerwin@unco.edu

Kruger, Elise

Klioze, Steven                                                                                                                                               

Mackessy, Stephen P.

Department of Biological Sciences                                                                                                            

University of Northern Colorado                                                                                                     

Greeley, Colorado USA

Despite the large strides made in the characterization and analysis of a wide diversity of snakes and their venoms, many species in more remote locations have yet to be investigated. Honduras is home to two medically significant vipers, Bothriechis thalassinus and Metlapilcoatlus indomitus, and their venoms have only recently been analyzed. Collaborations with Honduran serpentariums have yielded venoms samples from multiple individuals from both species across different life stages, allowing for analysis into their composition and investigation of potential ontogenetic shifts. SDS-PAGE, RP-HPLC, and mass spectrometry provided compositional data for each venom, along with quantification of enzymatic activity through toxin specific biochemical assays. While the venoms of Bothriechis thalassinus showed little to no evidence of ontogeny, the overall composition falls under the type I phenotype as indicated by the large amounts of metalloproteases of the P-III and P-I classes. The venoms of Metlapilcoatlus indomitus however, displays evidence of an ontogenetic shift that contradicts previous findings, with neonates exhibiting large amounts of P-III and P-I metalloproteases along with trace amounts of phospholipase A2 (PLA2s). This venom composition undergoes a consistent shift in the adult population, where the ratio of these two toxin families switches and PLA2s become a dominant component. While found in overlapping regions of Central America, little is known about the natural histories of these two species. This venomic analysis will provide insights into the realized niche that each organism fills. Within Metlapilcoatlus indomitus, this shift in overall composition may reveal an evolving specificity of diet throughout their early life and create a better assessment of the potential envenomation capabilities of each species.