Detection, using antibodies, of pharmacologically active sites, apart from the catalytic site, on venom phospholipase...

Polyclonal antibodies to a purified neurotoxic phospholipase A2 VRV PL-V from Vipera russelli venom were raised in rabbits. The gamma globulin fraction from the serum of the rabbits injected with VRV PL-V-toxoid (anti VRV PL-V antibodies) is termed anti PL-V Ig. Anti PL-V Ig neutralized the neurotoxic symptoms and lethal effects of neurotoxic PLA2s (VRV PL-V, VRV PL-VI and VRV PL-VIIIa) and neurotoxic symptoms of whole V. russelli venom, without affecting their phospholipase A2 activities. Their edema inducing activity was also unaffected. Anti VRV PL-V-antibodies inhibited the anticoagulant potencies of the neurotoxic PLA2s (VRV PL-V, VRV PL-VI and VRV PL-VIIIa) from V. russelli venom and VRV PL-V-toxoid. The myonecrotic activity of VRV PL-V, VRV PL-VIIIa and whole venom remain unaffected in presence of anti PL-V Ig. The hemoglobinuria induced in rabbits by injection of VRV PL-V-toxoid was inhibited by anti VRV PL-V antibodies. These results indicate the presence of multiple pharmacological sites apart from the catalytic site on V. russelli PLA2 molecules.