Ability of rabbit antiserum against crotapotin to neutralize the neurotoxic, myotoxic and phospholipase A2 activities of crotoxin from Crotalus durissus cascavella snake venom

The toxicity of crotoxin, the major toxin of Crotalus durissus terrificus (South American rattlesnake) venom, is mediated by its basic phospholipase A2 (PLA2) subunit. This PLA2 is non-covalently associated with crotapotin, an acidic, enzymatically inactive subunit of the crotoxin complex. In this work, rabbit antiserum raised against crotapotin purified from Crotalus durissus cascavella venom was tested for its ability to neutralize the neurotoxicity of this venom and its crotoxin in vitro. The ability of this antiserum to inhibit the enzymatic activity of the crotoxin complex and PLA2 alone was also assessed, and its potency in preventing myotoxicity was compared with that of antisera raised against crotoxin and PLA2. Antiserum to crotapotin partially neutralized the neuromuscular blockade caused by venom and crotoxin in electrically stimulated mouse phrenic nerve-hemidiaphragm preparations and prevented the venom-induced myotoxicity, but did not inhibit the enzymatic activity of crotoxin and purified PLA2. In contrast, previous findings showed that antisera against crotoxin and PLA2 from C. d. cascavella effectively neutralized the neuromuscular blockade and PLA2 activity of this venom and its crotoxin. The partial neutralization of crotoxin-mediated neurotoxicity by antiserum to crotapotin probably reduced the binding of crotoxin to its receptor following interaction of the antiserum with the crotapotin moiety of the complex.