Russell’s viper (Daboia russelii)

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Studies carried out in mice have demonstrated that two approved drugs, varespladib and marimastat, effectively counter the systemic and lethal effects of Russell’s viper venom, individually or in combination.

• Russell’s vipers are responsible for over half of India’s snakebite cases.
• Components - Phospholipase A₂ (PLA₂), and Snake Venom Metalloproteinase (SVMPs) are two main components of Russell’s viper snake venom.
• Effects - These toxins interfere with components of the blood clotting cascade to induce anticoagulant and haemorrhagic effects in humans.
• Drugs - While the varespladib drug inhibits PLA₂, the marimastat drug inhibits SVMP.
• In the latest study, Russell’s viper venom from Punjab and Tamil Nadu exhibited the highest PLA₂ activity, followed by other regions Kerala, Maharashtra, Goa, and Madhya Pradesh.
• Russell’s viper snake venom from all other regions exhibited minimal PLA₂ activity.
• Proteinase activity was highest in Karnataka, followed by the Rajasthan, Madhya Pradesh, Goa, and Andhra Pradesh regions.
• In contrast, venom from Tamil Nadu exhibited little to no activity, while venom samples from other regions exhibited modest proteolytic activity.
• The PLA2 inhibitor varespladib was found to neutralise even the high PLA2 activity of the venom found in Tamil Nadu and Punjab.
• The varespladib drug effectively inhibited the modest PLA2 activity of the venom from other Indian regions.
• In the case of the matrix metalloprotease-inhibiting drug, marimastat, the drug effectively inhibited the venom in a concentration-dependent manner.
• The drug was effective even when the proteolytic activity was high, as seen in Karnataka.
• As expected, the drug exhibited highly potent inhibitory effects against the venom with moderate activity, as seen in Madhya Pradesh, Rajasthan, and Goa.
• Overall, the drugs varespladib and marimastat when used individually or in a therapeutic drug combination were found to be very effective in reducing venom-induced cytotoxicity, venom-induced coagulopathy, and fibrinogenolysis.
• When used individually, the drugs were effective in reducing the venom-induced cytotoxicity by snake populations from some regions while being less effective in the case of venom from some other regions.
• However, the therapeutic combination of varespladib and marimastat nearly completely inhibited these activities.

Reference

The Hindu | Hope to cure Russell’s viper bites