Exploring the venom of the forest cobra snake: Toxicovenomics and antivenom profiling of Naja melanoleuca

A toxicovenomic analysis of the venom of the forest cobra, N. melanoleuca, was performed, revealing the presence of a total of 52 proteins by proteomics analysis. The most abundant proteins belong to the three-finger toxins (3FTx) (57.1 wt%), which includes post-synaptically acting α-neurotoxins. Phospholipases A₂ (PLA₂) were the second most abundant group of proteins (12.9 wt%), followed by metalloproteinases (SVMPs) (9.7 wt%), cysteine-rich secretory proteins (CRISPs) (7.6 wt%), and Kunitz-type serine proteinase inhibitors (3.8 wt%). A number of additional protein families comprised each < 3 wt% of venom proteins. A toxicity screening of the fractions, using the mouse lethality test, identified toxicity in RP-HPLC peaks 3, 4, 5 and 8, all of them containing α-neurotoxins of the 3FTx family, whereas the rest of the fractions did not show toxicity at a dose of 0.53 mg/kg. Three polyspecific antivenoms manufactured in South Africa and India were tested for their immunoreactivity against crude venom and fractions of N. melanoleuca. Overall, antivenoms immunorecognized all fractions in the venom, the South African antivenom showing a higher titer against the neurotoxin-containing fractions. This toxicovenomic study identified the 3FTx group of α-neurotoxins in the venom of N. melanoleuca as the relevant targets to be neutralized.