Search

Here we describe and compare the venomic and antivenomic characteristics of both neonate and adult Prairie Rattlesnake ( Crotalus viridis viridis ) venoms. Although both neonate and adult venoms contain unique components, similarities among protein family content were seen. Both neonate and adult venoms consisted of myotoxin, bradykinin-potentiating peptide (BPP), phospholipase A 2 (PLA 2 ), Zn 2 + -dependent metalloproteinase (SVMP), serine proteinase, L-amino acid oxidase (LAAO), cysteine-rich secretory protein (CRISP) and disintegrin families. Quantitative differences, however, were observed, with venoms of adults containing significantly higher concentrations of the non-enzymatic toxic compounds and venoms of neonates containing higher concentrations of pre-digestive enzymatic proteins such as SVMPs. To assess the relevance of this venom variation in the context of snakebite and snakebite treatment, we tested the efficacy of the common antivenom CroFab® for recognition of both adult and neonate venoms in vitro . This comparison revealed that many of the major protein families (SVMPs, CRISP, PLA 2 , serine proteases, and LAAO) in both neonate and adult venoms were immunodepleted by the antivenom, whereas myotoxins, one of the major toxic components of C . v . viridis venom, in addition to many of the small peptides, were not efficiently depleted by CroFab®. These results therefore provide a comprehensive catalog of the venom compounds present in C . v . viridis venom and new molecular insight into the potential efficacy of CroFab® against human envenomations by one of the most widely distributed rattlesnake species in North America. Biological significance Comparative proteomic analysis of venoms of neonate and adult Prairie Rattlesnake ( Crotalus viridis viridis ) from a discrete population in Colorado revealed a novel pattern of ontogenetic shifts in toxin composition for viperid snakes. The observed stage-dependent decrease of the relative content of disintegrins, catalytically active D49-PLA 2 s, L-amino acid oxidase, and SVMPs, and the concomitant increase of the relative abundance of paralytic small basic myotoxins and ohanin-like toxin, and hemostasis-disrupting serine proteinases, may represent an age-dependent strategy for securing prey and avoiding injury as the snake switches from small ectothermic prey and newborn rodents to larger endothermic prey. Such age-dependent shifts in venom composition may be relevant for antivenom efficacy and treatment of snakebite. However, applying a second-generation antivenomics approach, we show that CroFab®, developed against venom of three Crotalus and one Agkistrodon species, efficiently immunodepleted many, but not all, of the major compounds present in neonate and adult C . v . viridis venoms. [ABSTRACT FROM AUTHOR]

On account of their unique anatomy, physiology, natural history, ecology, and behavior, rattlesnakes make ideal subjects for a variety of different scientific disciplines. The prairie rattlesnake (Crotalus viridis) in Colorado was selected for investigation of its relationship to colonies of black-tailed prairie dogs (Cynomys ludovicianus) with regard to spatial ecology. A total of 31 snakes were anesthetized and had radiotransmitters surgically implanted. In addition, at the time of their capture, all snakes underwent the following: (1) they had bacterial culture taken from their mouths for potential isolation of pathogenic bacteria; (2) similarly, they had cloacal bacterial cultures taken to assess potentially harmful bacteria passed in the feces; and (3) they had blood samples drawn to investigate the presence of any zoonotic agents in the serum of the snakes. The results of the study and their implications are discussed here. Traditionally, a low incidence of bacterial wound infection has been reported following snakebite. Nevertheless, the oral cavity of snakes has long been known to house a wide variety of bacterial flora. In our study, 10 different bacterial species were isolated from the mouths of the rattlesnakes, 6 of which are capable of being zoonotic pathogens and inducing human disease. More studies are necessary to see why more rattlesnake bites do not become infected despite the presence of such pathogenic bacteria. The results of fecal bacteria isolated revealed 13 bacterial species, 12 of which can cause disease in humans. Of the snakes whose samples were cultured, 26% were positive for the presence of the pathogen Salmonella arizonae, one of the causative agents of reptile-related salmonel-losis in humans. It has long been reported that captive reptiles have a much higher incidence than wild, free-ranging species. This study shows the incidence of Salmonella in a wild, free-ranging population of rattlesnakes. In addition, Stenotrophomonas maltophilia was isolated. This bacterium is associated with wound and soft tissue infections that can lead to sepsis, endocarditis, meningitis, and peritonitis. In addition, this bacterium has been increasingly implicated as an opportunistic pathogen to humans during pregnancies, hospitalizations, malignancies and chemotherapy, chronic respiratory diseases, and presurgical endotracheal intubation. Furthermore, S. maltophilia has an intense resistance to broad-spectrum antibiotics, the results of our study showed the bacterium was resistant to multiple antibiotics. Our results indicate that anyone working with snake feces, dead skin, or their carcasses must follow reasonable hygiene protocols. Rattlesnakes tested for West Nile antibodies had positive results but these were invalidated owing to possible cross-reactivity with other unknown viruses, interference with snake serum proteins, and the fact that the test was not calibrated for rattlesnake serum. Still, the interesting implication remains, should we be regularly testing these animals as sentinels against potentially zoonotic diseases. The results of this study clearly show the value of veterinarians in a multidisciplinary study of this sort and the particular skill set they can offer. Veterinarians must get involved in conservation studies if the biodiversity of the planet is to be preserved. [ABSTRACT FROM AUTHOR]