Ontogenetic influence in Crotalus durissus ruruima snake venom: an intermediate between north and south venom pattern of rattlesnake

The genus Crotalus comprises venomous pit vipers widely distributed discontinuously from southern Canada to northern Argentina. A dichotomy in Crotalus venom is observed, divided in type I and type II, and these different types could be correlated with geographic distribution and ontogeny of these snakes. C. d. ruruima inhabits Roraima state, Northen of Brazil, close to the Equatorial line and to North American Rattlesnakes. Brazilian crotalic antivenom is produced by the mixture of C. d. terrificus and C. d. collilineatus venoms, not including other subspecies. The knowledge of snake venom variation is important for the treatment of snakebite envenomation and for the correct selection of specimens for the antivenom production. Thus, this work compared the enzymatic activity and composition of C. d. ruruima venom at different ages to improve our knowledge about this species comparing it with a typical southern rattlesnake (C. d. collilineatus). C. d. ruruima juveniles' venom have higher LAAO and PLA₂ activities than adults, while, C. d. collilineatus juveniles have higher coagulant activity than adults. Slight changes in venom composition are noticeable in SDS-PAGE and FPLC of both subspecies, with C. d. ruruima having a greater presence of bands, mainly of proteins with high molecular weight. In addition, C. d. ruruima showed higher PLA₂, LAAO and proteolytic activities than C. d. collilineatus. The hyaluronidase and thrombin-like activities did not show differences. Although the variations found, no difference in immunorecognition was observed between the venoms in different ages and subspecies. Despite inhabiting South America, C. d. ruruima's habitat is closer to the Equatorial line, and the findings in this work suggest that this species may represent a transition between proteolytic to neurotoxic venom phenotype, following the north-south distribution of rattlesnakes.