Neutralization of crotamine by polyclonal antibodies generated against two whole rattlesnake venoms and a novel recombinant fusion protein

Venom variation and ontogenetic changes in the Crotalus molossus complex: Insights into composition, activities, and antivenom neutralization

The Crotalus molossus complex consists of five to seven phylogenetically related lineages of black-tailed rattlesnakes widely distributed in Mexico. While previous studies have noted venom variation within specific lineages of the Crotalus molossus complex, a comprehensive characterization of interspecific and ontogenetic venom variations, their functional implications, and the neutralizing ability of the Mexican antivenom against these variants remains largely unexamined. Herein, using two proteomic approaches for five lineages (C. basiliscus, C. m. molossus, C. m. nigrescens, C. m. oaxacus, and C. ornatus) of the C. molossus complex we characterized the number of toxins and their relative abundance in the venom of individuals of varying sizes. All five lineages undergo ontogenetic venom composition shifts associated with snake length. However, the pattern of ontogenetic shifts varied among lineages. In some lineages, these shifts led to significant differences in proteolytic, phospholipase A2, and fibrinogenolytic activities. Venom in smaller C. basiliscus, C. m. nigrescens, and C. m. oaxacus individuals had lower LD50 values (more lethal) in mice. Whereas the venom lethality of C. m. nigrescens (both juvenile and adult) and C. m. oaxacus (adult) was several times higher in a mammalian (mouse) model than in a reptilian (iguana) model. Antivipmyn® showed different neutralizing potencies toward venom pools. Overall, our results indicated that even among closely related rattlesnake lineages, venom phenotypes may vary greatly, impacting their function and the efficacy of antivenom neutralization.

Bioprospection of rattlesnake venom peptide fractions with anti-adipose and anti-insulin resistance activity in vitro

Animal venoms are natural products that have served as a source of novel molecules that have inspired novel drugs for several diseases, including for metabolic diseases such as type-2 diabetes and obesity. From venoms, toxins such as exendin-4 (Heloderma suspectum) and crotamine (Crotalus durissus terrificus) have demonstrated their potential as treatments for obesity. Moreover, other toxins such as Phospholipases A2 and Disintegrins have shown their potential to modulate insulin secretion in vitro. This suggests an unexplored diversity of venom peptides with a potential anti-obesogenic in Mexican rattlesnake venoms. For that reason, this study explored the in vitro effect of Crotalus venom peptide-rich fractions on models for insulin resistance, adipocyte lipid accumulation, antioxidant activity, and inflammation process through nitric oxide production inhibition. Our results demonstrated that the peptide-rich fractions of C. aquilus, C. ravus, and C. scutulatus scutulatus were capable of reverting insulin resistance, enhancing glucose consumption to normal control; C. culminatus, C. molossus oaxacus, and C. polystictus diminished the lipid accumulation on adipocytes by 20%; C. aquilus, C. ravus, and C. s. salvini had the most significant cellular antioxidant activity, having nearly 80% of ROS inhibition. C. aquilus, C. pyrrhus, and C. s. salvini inhibited nitric oxide production by about 85%. We demonstrated the potential of these peptides from Crotalus venoms to develop novel drugs to treat type-2 diabetes and obesity. Moreover, we described for the first time that Crotalus venom peptide fractions have antioxidant and inflammatory properties in vitro models.

Revolutionizing snakebite care with novel antivenoms: Breakthroughs and barriers

Snakebite envenoming (SBE) is a global public health concern, primarily due to the lack of effective antivenom for treating snakebites inflicted by medically significant venomous snakes prevalent across various geographic locations. The rising demand for safe, cost-effective, and potent snakebite treatments highlights the urgent need to develop alternative therapeutics targeting relevant toxins. This development could provide promising discoveries to create novel recombinant solutions, leveraging human monoclonal antibodies, synthetic peptides and nanobodies. Such technologies as recombinant DNA, peptide and epitope mapping phage display etc) have the potential to exceed the traditional use of equine polyclonal antibodies, which have long been used in antivenom production. Recombinant antivenom can be engineered to target certain toxins that play a critical role in snakebite pathology. This approach has the potential to produce antivenom with improved efficacy and safety profiles. However, there are limitations and challenges associated with these emerging technologies. Therefore, identifying the limitations is critical for overcoming the associated challenges and optimizing the development of recombinant antivenoms. This review is aimed at presenting a thorough overview of diverse technologies used in the development of recombinant antivenom, emphasizing their limitations and offering insights into prospects for advancing recombinant antivenoms.

Venom of the neotropical rattlesnake, Crotalus culminatus: Intraspecific variation, neutralization by antivenoms, and immunogenicity in rabbits

Crotalus culminatus is a medically significant species of rattlesnake in Mexico [1]. While the proteomic composition of its venom has been previously reported for both juvenile and adult specimens, there has been limited research into its functional properties, with only a few studies, including one focusing on coagulotoxicity mechanisms. In this study, we aimed to compare the biochemical and biological activities of the venom of juvenile and adult snakes. Additionally, we assessed antibody production using the venoms of juveniles and adults as immunogens in rabbits. Our findings reveal lethality and proteolytic activity differences between the venoms of juveniles and adults. Notably, juvenile venoms exhibited high proportions of crotamine, while adult venoms displayed a reduction of this component. A commercially available antivenom demonstrated effective neutralization of lethality of both juvenile and adult venoms in mice. However, it failed to neutralize the paralytic activity induced by crotamine, which, in contrast, was successfully inhibited by antibodies obtained from hyperimmunized rabbits. These results suggest the potential inclusion of C. culminatus venom from juveniles in commercial antivenom immunization schemes to generate antibodies targeting this small myotoxin.

A Review of Rattlesnake Venoms

Venom components are invaluable in biomedical research owing to their specificity and potency. Many of these components exist in two genera of rattlesnakes, Crotalus and Sistrurus, with high toxicity and proteolytic activity variation. This review focuses on venom components within rattlesnakes, and offers a comparison and itemized list of factors dictating venom composition, as well as presenting their known characteristics, activities, and significant applications in biosciences. There are 64 families and subfamilies of proteins present in Crotalus and Sistrurus venom. Snake venom serine proteases (SVSP), snake venom metalloproteases (SVMP), and phospholipases A2 (PLA2) are the standard components in Crotalus and Sistrurus venom. Through this review, we highlight gaps in the knowledge of rattlesnake venom; there needs to be more information on the venom composition of three Crotalus species and one Sistrurus subspecies. We discuss the activity and importance of both major and minor components in biomedical research and drug development.

Intraspecific venom variation of Mexican West Coast Rattlesnakes (Crotalus basiliscus) and its implications for antivenom production

Intraspecific variation in snake venoms has been widely documented worldwide. However, there are few studies on this subject in Mexico. Venom characterization studies provide important data used to predict clinical syndromes, to evaluate the efficacy of antivenoms and, in some cases, to improve immunogenic mixtures in the production of antivenoms. In the present work, we evaluated the intraspecific venom variation of Crotalus basiliscus, a rattlesnake of medical importance and whose venom is used in the immunization of horses to produce one of the Mexican antivenoms. Our results demonstrate that there is variation in biological and biochemical activities among adult venoms and that there is an ontogenetic change from juvenile to adult venoms. Juvenile venoms were more lethal and had higher percentages of crotamine and crotoxin, while adult venoms had higher percentages of snake venom metalloproteases (SVMPs). Additionally, we documented crotoxin-like PLA₂ variation in which specimens from Zacatecas, Sinaloa and Michoacán (except 1) lacked the neurotoxin, while the rest of the venoms had it. Finally, we evaluated the efficacy of three lots of Birmex antivenom and all three were able to neutralize the lethality of four representative venoms but were not able to neutralize crotamine. We also observed significant differences in the LD₅₀ values neutralized per vial among the different lots. Based on these results, we recommend including venoms containing crotamine in the production of antivenom for a better immunogenic mixture and to improve the homogeneity of lots.