Equine antibodies to Bothrops asper myotoxin II: isolation from polyvalent antivenom and neutralizing ability

Equine antibodies to B. asper myotoxin II were isolated from polyvalent antivenom by affinity chromatography. Purified antibodies were among the most acidic serum immunoglobulins, migrating between the beta- and alpha 2-globulin regions by zone electrophoresis. This might be related to the fact that myotoxin II is a very basic antigen. At an antibody/toxin molar ratio of two or higher, myotoxic effect of myotoxin II was neutralized completely. Antibodies also neutralized myotoxic activity of crude venom in mice, reducing the effect by about 75% when a proportion of 16 mg antibodies/mg venom was tested. Despite the lack of phospholipase A2 activity of myotoxin II, antibodies were able to neutralize this enzymatic activity of myotoxin I, a previously described isoform. This finding is in agreement with the notion that myotoxin II is a phospholipase A2-analog devoid of this enzyme activity.