Abstract
BackgroundThe Eastern Russell’s viper, Daboia siamensis, is a WHO Category 1 medically important venomous snake. It has a wide but disjunct distribution in Southeast Asia. The specific antivenom, D. siamensis Monovalent Antivenom (DsMAV-Thailand) is produced in Thailand but not available in Indonesia, where a heterologous trivalent antivenom, Serum Anti Bisa Ular (SABU), is used instead. This study aimed to investigate the geographical venom variation of D. siamensis from Thailand (Ds-Thailand) and Indonesia (Ds-Indonesia), and the immunorecognition of the venom proteins by antivenoms.Methods: The venom proteins were decomplexed with reverse-phase high-performance liquid chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by in-solution tryptic digestion, nano-liquid chromatography-tandem mass spectrometry and protein identification. The efficacies of DsMAV-Thailand and SABU in binding the various venom fractions were assessed using an enzyme-linked immunosorbent assay optimized for immunorecognition profiling. Results: The two most abundant protein families in Ds-Thailand venom are phospholipase A2 (PLA2) and Kunitz-type serine protease inhibitor (KSPI). Those abundant in Ds-Indonesia venom are PLA2 and serine protease. KSPI and vascular endothelial growth factor were detected in Ds-Thailand venom, whereas L-amino acid oxidase and disintegrin were present in Ds-Indonesia venom. Common proteins shared between the two included snaclecs, serine proteases, metalloproteinases, phosphodiesterases, 5’nucleotidases and nerve growth factors at varying abundances. DsMAV-Thailand exhibited strong immunorecognition of the major protein fractions in both venoms, but low immunoreactivity toward the low molecular weight proteins e.g. KSPI and disintegrins. On the other hand, SABU was virtually ineffective in binding all fractionated venom proteins. Conclusion: D. siamensis venoms from Thailand and Indonesia varied geographically in the protein subtypes and abundances. The venoms, nevertheless, shared conserved antigenicity that allowed effective immunorecognition by DsMAV-Thailand but not by SABU, consistent with the neutralization efficacy of the antivenoms. A specific, appropriate antivenom is needed in Indonesia to treat Russell’s viper envenomation.
Highlights
The Eastern Russell’s viper, Daboia siamensis, is a WHO Category 1 medically important venomous snake
Kunitz-type serine protease inhibitor (KSPI) and vascular endothelial growth factor were detected in Ds-Thailand venom, whereas L-amino acid oxidase and disintegrin were present in Ds-Indonesia venom
The present findings reveal that most protein families – i.e. Phospholipase A2 (PLA2), snaclec, snake venom serine protease (SVSP), snake venom metalloproteinase (SVMP), PDE, 5’snake venom 5’ nucleotidase (NUC) and venom nerve growth factor (VNGF) – were well conserved between the two geographical populations despite their wide disjunctive distribution
Summary
The Eastern Russell’s viper, Daboia siamensis, is a WHO Category 1 medically important venomous snake It has a wide but disjunct distribution in Southeast Asia. Limitis, sublimitis, siamensis and formosensis) have been collectively elevated to full species status, namely Daboia siamensis (Eastern Russell’s viper). The distribution of D. siamensis is wide but extremely disjunctive It is found in Guangdong and Guangxi (southern China), and the insular population found in Taiwan marks the easternmost distribution of this species. In the south, it is distributed in Indochina subcontinent covering Myanmar (Burma), Thailand, Laos and western Cambodia but not in Vietnam, and it is absent throughout Malaysian Peninsula, Borneo and the Philippines. Further to the south across the South China Sea and the Javan Sea, the species emerges in isolated populations in the eastern Java and some islets of Lesser Sunda, on the Indonesian Archipelago
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