Effect of heating on the toxic, immunogenic and immunosuppressive activities of Crotalus durissus terrificus venom.

The venom of South American rattlesnake Crotalus durissus terrificus is very toxic but poorly immunogenic and it has an immunosuppressive ability. The heating of venom at 56, 70 or 100 degrees C for 30 min caused a diminution in the lethal, phospholipase A(2) and myotoxic activities. SDS-PAGE analysis of the heated venom showed that the proteins of higher molecular weights were the most affected by heating whereas proteins with lower molecular weights (20,000-14, 000) were the most resistant to heating. The immunosuppressive effect was studied in mice immunized with human serum albumin (HSA) 1 h after receiving either heated venom or heated crotoxin. The heating of venom at 70 or 100 degrees C reduced its immunosuppressive effect whereas crotoxin had its suppressive effect reduced only when heated at 100 degrees C. The heating of venom at 56, 70 or 100 degrees C did not change its immunogenicity.These results suggest that heat treatment may be a useful technique to help in the production of antiserum to crotalid venom.