The immunochemical reactivity and neutralizing capacity of polyvalent Vipera antivenom (Vipera ammodytes, Vipera aspis, Vipera berus, Vipera lebetina, and Vipera xanthina) were tested on the enzymatic and biological activities of Crotalus durissus terrificus and the following Bothrops venoms from Argentina (Bothrops alternatus, Bothrops ammodytoides, Bothrops neuwiedii, Bothrops jararaca, Bothrops jararacussu, and Bothrops moojeni). The Vipera antivenom reacted weakly when tested by double immunoprecipitation (DIP) and reacted with all the venoms when tested by ELISA. Several components in all the venoms studied were recognized in Western blots. Vipera antivenom deactivated to different degrees in vitro procoagulant, (indirect) hemolytic, and proteolytic activities in all the venoms studied. Preincubation of Bothrops alternatus venom with Vipera antivenom neutralized a lethal potency of 4.5 LD50 in mice with an ED50 of 1.25 <FONT FACE="Symbol">±</FONT> 0.25 <FONT FACE="Symbol">m</FONT>l per <FONT FACE="Symbol">m</FONT>g of venom, and with 1.0 <FONT FACE="Symbol">m</FONT>l/<FONT FACE="Symbol">m</FONT>g inhibited 54% of the hemorragic activity and 48% of necrotic activity. Vipera antivenom (2.0 <FONT FACE="Symbol">m</FONT>l per <FONT FACE="Symbol">m</FONT>g toxin) inhibited the phospholipase A2 activity of purified crotoxin and decreased its lethal potency by 60%, while the neutralizing capacity on the lethal potency of crude Crotalus durissus terrificus venom was poor even at a level of 5.0 <FONT FACE="Symbol">m</FONT>l/<FONT FACE="Symbol">m</FONT>g of venom.
antivenom; Vipera; Bothrops; Crotalus; cross-reactivity; cross-neutralization
