Citation

Tan CH, Tan KY, Lim SE, Tan NH. J. Proteomics 2015; 126: 121-130.

Affiliation

Department of Molecular Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; University of Malaya Centre for Proteomics Research, University of Malaya, 50603 Kuala Lumpur, Malaysia.

Copyright

(Copyright © 2015, Elsevier Publishing)

DOI

10.1016/j.jprot.2015.05.035

PMID

26047715

Abstract

The venom proteome of Hydrophis schistosus (synn: Enhydrina schistosa) captured in Malaysian waters was investigated using reverse-phase HPLC, SDS-PAGE and high-resolution liquid chromatography-tandem mass spectrometry. The findings revealed a minimalist profile with only 18 venom proteins. These proteins belong to 5 toxin families: three-finger toxin (3FTx), phospholipase A2 (PLA2), cysteine-rich secretory protein (CRISP), snake venom metalloprotease (SVMP) and L-amino acid oxidase (LAAO). The 3FTx (3 short neurotoxins and 4 long neurotoxins) constitute 70.5% of total venom protein, 55.8% being short neurotoxins and 14.7% long neurotoxins. The PLA2 family consists of four basic (21.4%) and three acidic (6.1%) isoforms. The minor proteins include one CRISP (1.3%), two SVMPs (0.5%) and one LAAO (0.2%). This is the first report of the presence of long neurotoxins, CRISP and LAAO in H. schistosus venom. The neurotoxins and the basic PLA2 are highly lethal in mice with an intravenous median lethal dose of <0.2 μg/g. Cross-neutralization by heterologous elapid antivenoms (Naja kaouthia monovalent antivenom and Neuro polyvalent antivenom) was moderate against the long neurotoxin and basic PLA2, but weak against the short neurotoxin, indicating that the latter is the limiting factor to be overcome for improving the antivenom cross-neutralization efficacy. BIOLOGICAL SIGNIFICANCE: In Malaysia, the beaked sea snake, Hydrophis schistosus, is commonly encountered in coastal waters. Envenomation by this species has been reported sporadically but it represents a long-standing occupational hazard for fishermen and those engaged in sea water activities. The only indicated effective treatment is the sea snake antivenom manufactured by the Australian Commonwealth Serum Laboratory; it is however extremely costly and its storage in local hospitals remains suboptimal. It has been reported in animal studies that certain elapid antivenoms could cross-neutralize the sea snake venom. This study profiled the venom of H. schistosus through a comprehensive proteomic approach: the venom was first fractionated by reverse-phase HPLC and SDS-PAGE, followed by protein identification using mass spectrometry technology. Through this we isolated and identified the major lethal toxins i.e. the long and short neurotoxins, and basic phospholipases A2. Further assessment demonstrated that these toxins can be neutralized to different degrees by two regionally available heterologous antivenoms. The comprehensive knowledge of the toxin composition and cross-neutralization profile of H. schistosus toxins will contribute to the better understanding of the pathophysiology and the management of sea snake envenomation.

Language: en