Venomics of Trimeresurus (Popeia) nebularis, the Cameron Highlands Pit Viper from Malaysia: Insights into Venom Proteome, Toxicity and Neutralization of Antivenom.

Choo Tan,Ahmad Ismail,Sumana Khomvilai,Tzu Ng,Nget Tan,Evan Quah,Visith Sitprija,Kae Tan

doi:10.3390/toxins11020095

Abstract

Trimeresurus nebularis is a montane pit viper that causes bites and envenomation to various communities in the central highland region of Malaysia, in particular Cameron’s Highlands. To unravel the venom composition of this species, the venom proteins were digested by trypsin and subjected to nano-liquid chromatography-tandem mass spectrometry (LC-MS/MS) for proteomic profiling. Snake venom metalloproteinases (SVMP) dominated the venom proteome by 48.42% of total venom proteins, with a characteristic distribution of P-III: P-II classes in a ratio of 2:1, while P-I class was undetected. Snaclecs constituted the second most venomous protein family (19.43%), followed by snake venom serine proteases (SVSP, 14.27%), phospholipases A2 (5.40%), disintegrins (5.26%) and minor proteins including cysteine-rich secretory proteins, L-amino acid oxidases, phosphodiesterases, 5′-nucleotidases. The venomic profile correlates with local (painful progressive edema) and systemic (hemorrhage, coagulopathy, thrombocytopenia) manifestation of T. nebularis envenoming. As specific antivenom is unavailable for T. nebularis, the hetero-specific Thai Green Pit viper Monovalent Antivenom (GPVAV) was examined for immunological cross-reactivity. GPVAV exhibited good immunoreactivity to T. nebularis venom and the antivenom effectively cross-neutralized the hemotoxic and lethal effects of T. nebularis (lethality neutralizing potency = 1.6 mg venom per mL antivenom). The findings supported GPVAV use in treating T. nebularis envenoming.

Highlights

A large number of the Asian or oriental pit vipers (Reptilia: Serpentes: Viperidae: Crotalinae), in particular those described as having “lance-headed appearance,” were in the past considered congeneric and placed within Trimeresurus sensu lato (s.l.)
Nano-liquid chromatography-tandem mass spectrometry (LC-MS/MS) of the venom identified a total of 44 proteins in the venom, in which 40 proteins were clustered into 9 different toxin families, namely snake venom metalloproteinase (SVMP, 48.42% of total venom proteins), snake venom C-type lectin/lectin-like protein, snake venom serine protease (SVSP, 14.3%), phospholipase A2 (PLA2, 5.4%), disintegrin (5.26%), cysteine-rich secretory protein (CRISP, 4.31%), L-amino acid oxidase (LAAO, 0.99%), phosphodiesterase (PDE, 0.37%) and
Snake venom metalloproteinases (SVMP) formed the main bulk of T. nebularis venom proteome

Summary

Introduction

A large number of the Asian or oriental pit vipers (Reptilia: Serpentes: Viperidae: Crotalinae), in particular those described as having “lance-headed appearance,” were in the past considered congeneric and placed within Trimeresurus sensu lato (s.l.). Multiple systematic revisions took place over the years on Trimeresurus complex with various genera, subgenera and species being erected or collapsed, overwhelming the field with a continuous taxonomic flux [1,2,3]. Taxonomic advancements have improved knowledge on field identification and biogeographical distribution of the various species therein [1,2,8]. This is significant to the toxinologist community, as in snake envenomation species identity is crucial for accurate diagnosis and treatment [9]. Extensive biomedical studies have shown that venom compositions can vary greatly between and even within species, and the venom variation usually correlates with differences in venom toxicity and clinical manifestation of snakebite envenoming [10,11,12,13]

Methods

Results

Conclusion