Immunization of equines with phospholipase A2 protects against the lethal effects of Crotalus durissus terrificus venom.

Equines (2 horses and 2 donkeys) immunized with whole Crotalus durissus terrificus venom or its phospholipase A2 component either presented an increased survival time determined 3 days after challenge or were totally resistant to a challenging lethal dose of 200 mg crude venom 270 days after the initial immunization or 90 days after the last booster injection. The resistance was demonstrable on the basis of a good correlation with antibody titers determined by the ELISA method but not with the flocculation and neutralization assays. Since phospholipase A2 is essentially nontoxic, it can be used as a substitute for whole venom for the production of commercial antisera and as an immunizing agent in prophylactic programs.