Ninety-five
venom samples from eight snake genera (Agkistrodon, Bitis, Bothrops, Calloselasma, Crotalus, Sistrurus, Naja and Vipera) including
venoms of Crotalus species of different geographical origin were assayed using immunodiffusion or an ELISA for the presence of the small basic
protein,
myotoxin alpha, known to cause muscle
necrosis. Of the eight genera investigated, only Crotalus and Sistrurus
venoms contained detectable amounts of
myotoxin alpha-like
proteins. The
venoms of 13 out of 17 rattlesnake species investigated contained
proteins immunologically similar to
myotoxin alpha, including 12 Crotalus species and one Sistrurus species. The highest amounts were detected in
venoms of C. exsul, C. viridis oreganus and C. v. viridis. Qualitative differences in the presence or absence of
myotoxin alpha-like
proteins were observed in the
venoms of C. cerastes, C. horridus, C. lepidus, C. mitchelli, C. scutulatus, C. viridis and S. catenatus specimens of different geographic origin. The toxin was not detected in the
venoms obtained from C. adamanteus, C. atrox, C. enyo or C. vegrandis specimens. The toxin appears to be widely distributed among rattlesnake species in the new world, but may vary qualitatively by geographical region in several species and subspecies.