Comparison of the lethal components in Vipera aspis aspis and Vipera aspis zinnikeri venom

Biological activities in Vipera a. aspis and V. a. zinnikeri venom were investigated and compared. Phospholipase A2 and lethal activities were found to be much higher in V. a. zinnikeri venom; the LD50 values for V. a. aspis and V. a. zinnikeri crude venom were 0.55 and 0.35 microgram/g, while PLA2 activities were 25.4 and 41.8 unit/mg, respectively. Other enzymatic and pharmacological activities investigated were similar in both venoms, suggesting that PLA2s might be responsible for the higher toxicity of V. a. zinnikeri venom. PLA2s contained in both venoms were compared immunologically, and the highly lethal phospholipase A2 (PLA2-I) purified from V. a. zinnikeri venom was not found in V. a. aspis venom as determined by antiserum for purified PLA2-I. The toxic effect of V. a. zinnikeri venom was inhibited by anti-PLA2-I, while the same antiserum could not prevent lethality by V. a. aspis venom. These results indicate that PLA2-I in V. a. zinnikeri venom possesses an important role in the lethal activity of this venom. Although V. a. zinnikeri is found in a defined area of France, it is possible that its lethal venom component developed differently than that of V. a. aspis.