1
|
Dashevsky D, Harris RJ, Zdenek CN, Benard-Valle M, Alagón A, Portes-Junior JA, Tanaka-Azevedo AM, Grego KF, Sant'Anna SS, Frank N, Fry BG. Red-on-Yellow Queen: Bio-Layer Interferometry Reveals Functional Diversity Within Micrurus Venoms and Toxin Resistance in Prey Species. J Mol Evol 2024; 92:317-328. [PMID: 38814340 PMCID: PMC11168994 DOI: 10.1007/s00239-024-10176-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 05/03/2024] [Indexed: 05/31/2024]
Abstract
Snakes in the family Elapidae largely produce venoms rich in three-finger toxins (3FTx) that bind to the α 1 subunit of nicotinic acetylcholine receptors (nAChRs), impeding ion channel activity. These neurotoxins immobilize the prey by disrupting muscle contraction. Coral snakes of the genus Micrurus are specialist predators who produce many 3FTx, making them an interesting system for examining the coevolution of these toxins and their targets in prey animals. We used a bio-layer interferometry technique to measure the binding interaction between 15 Micrurus venoms and 12 taxon-specific mimotopes designed to resemble the orthosteric binding region of the muscular nAChR subunit. We found that Micrurus venoms vary greatly in their potency on this assay and that this variation follows phylogenetic patterns rather than previously reported patterns of venom composition. The long-tailed Micrurus tend to have greater binding to nAChR orthosteric sites than their short-tailed relatives and we conclude this is the likely ancestral state. The repeated loss of this activity may be due to the evolution of 3FTx that bind to other regions of the nAChR. We also observed variations in the potency of the venoms depending on the taxon of the target mimotope. Rather than a pattern of prey-specificity, we found that mimotopes modeled after snake nAChRs are less susceptible to Micrurus venoms and that this resistance is partly due to a characteristic tryptophan → serine mutation within the orthosteric site in all snake mimotopes. This resistance may be part of a Red Queen arms race between coral snakes and their prey.
Collapse
Affiliation(s)
- Daniel Dashevsky
- Australian National Insect Collection, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT, 2601, Australia.
| | - Richard J Harris
- Venom Evolution Lab, School of the Environment, The University of Queensland, Saint Lucia, QLD, 4072, Australia
- Australian Institute of Marine Science, Cape Cleveland, QLD, 4810, Australia
| | - Christina N Zdenek
- Celine Frere Group, School of the Environment, The University of Queensland, Saint Lucia, QLD, 4072, Australia
| | - Melisa Benard-Valle
- Department of Biotechnology and Biomedicine, Technical University of Denmark, DK-2800, Kongens Lyngby, Region Hovedstaden, Denmark
| | - Alejandro Alagón
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, 62210, Cuernavaca, Morelos, Mexico
| | - José A Portes-Junior
- Laboratório de Coleções Zoológicas, Instituto Butantan, São Paulo, São Paulo, 05503-900, Brazil
| | - Anita M Tanaka-Azevedo
- Laboratório de Herpetologia, Instituto Butantan, São Paulo, São Paulo, 05503-900, Brazil
| | - Kathleen F Grego
- Laboratório de Herpetologia, Instituto Butantan, São Paulo, São Paulo, 05503-900, Brazil
| | - Sávio S Sant'Anna
- Laboratório de Herpetologia, Instituto Butantan, São Paulo, São Paulo, 05503-900, Brazil
| | - Nathaniel Frank
- MToxins Venom Lab, 717 Oregon Street, Oshkosh, WI, 54902, USA
| | - Bryan G Fry
- Venom Evolution Lab, School of the Environment, The University of Queensland, Saint Lucia, QLD, 4072, Australia
| |
Collapse
|
2
|
Hernández-Altamirano JA, Salazar-Valenzuela D, Medina-Villamizar EJ, Quirola DR, Patel K, Vaiyapuri S, Lomonte B, Almeida JR. First Insights into the Venom Composition of Two Ecuadorian Coral Snakes. Int J Mol Sci 2022; 23:ijms232314686. [PMID: 36499012 PMCID: PMC9740791 DOI: 10.3390/ijms232314686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 11/16/2022] [Accepted: 11/22/2022] [Indexed: 11/27/2022] Open
Abstract
Micrurus is a medically relevant genus of venomous snakes composed of 85 species. Bites caused by coral snakes are rare, but they are usually associated with very severe and life-threatening clinical manifestations. Ecuador is a highly biodiverse country with a complex natural environment, which is home to approximately 20% of identified Micrurus species. Additionally, it is on the list of Latin American countries with the highest number of snakebites. However, there is no local antivenom available against the Ecuadorian snake venoms, and the biochemistry of these venoms has been poorly explored. Only a limited number of samples collected in the country from the Viperidae family were recently characterised. Therefore, this study addressed the compositional patterns of two coral snake venoms from Ecuador, M. helleri and M. mipartitus, using venomics strategies, integrating sample fractionation, gel electrophoresis, and mass spectrometry. Chromatographic and electrophoretic profiles of these snake venoms revealed interspecific variability, which was ascertained by mass spectrometry. The two venoms followed the recently recognised dichotomic toxin expression trends displayed by Micrurus species: M. helleri venom contains a high proportion (72%) of phospholipase A2, whereas M. mipartitus venom is dominated by three-finger toxins (63%). A few additional protein families were also detected in these venoms. Overall, these results provide the first comprehensive views on the composition of two Ecuadorian coral snake venoms and expand the knowledge of Micrurus venom phenotypes. These findings open novel perspectives to further research the functional aspects of these biological cocktails of PLA2s and 3FTxs and stress the need for the preclinical evaluation of the currently used antivenoms for therapeutic purposes in Ecuador.
Collapse
Affiliation(s)
| | - David Salazar-Valenzuela
- Centro de Investigación de la Biodiversidad y Cambio Climático (BioCamb) e Ingeniería en Biodiversidad y Recursos Genéticos, Facultad de Ciencias de Medio Ambiente, Universidad Indoamérica, Quito 180103, Ecuador
| | | | - Diego R. Quirola
- Centro de Investigación de la Biodiversidad y Cambio Climático (BioCamb) e Ingeniería en Biodiversidad y Recursos Genéticos, Facultad de Ciencias de Medio Ambiente, Universidad Indoamérica, Quito 180103, Ecuador
| | - Ketan Patel
- School of Biological Sciences, University of Reading, Reading RG6 6UB, UK
| | | | - Bruno Lomonte
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San Jose 11501, Costa Rica
| | - José R. Almeida
- Biomolecules Discovery Group, Universidad Regional Amazónica Ikiam, Km 8 Via Muyuna, Tena 150101, Ecuador
- School of Pharmacy, University of Reading, Reading RG6 6UB, UK
- Correspondence:
| |
Collapse
|
3
|
Silva-Carvalho R, Gaspar MZ, Quadros LHB, Lobo LGG, Giuffrida R, Santarém CL, Silva EO, Gerez JR, Silva NJ, Hyslop S, Lomonte B, Floriano RS. Partial efficacy of a Brazilian coralsnake antivenom and varespladib in neutralizing distinct toxic effects induced by sublethal Micrurus dumerilii carinicauda envenoming in rats. Toxicon 2022; 213:99-104. [PMID: 35489427 DOI: 10.1016/j.toxicon.2022.04.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 03/31/2022] [Accepted: 04/20/2022] [Indexed: 11/26/2022]
Abstract
In this work, we report the efficacy of a combination of Brazilian therapeutic coralsnake antivenom (CAV) and varespladib (phospholipase A2 inhibitor - VPL) in partially neutralizing selected toxic effects of Micrurus dumerilii carinicauda coralsnake venom in rats. Venom caused local myonecrosis and systemic neurotoxicity, nephrotoxicity, and hepatotoxicity within 2 h of injection. CAV and VPL administered separately failed to prevent most of these alterations. However, a combination of CAV plus VPL offered variable protection against venom-induced coagulation disturbances, leukocytosis, and renal and hepatic morphological alterations.
Collapse
Affiliation(s)
- Rosimeire Silva-Carvalho
- Laboratory of Toxinology and Cardiovascular Research, Graduate Program in Health Sciences, University of Western São Paulo, Rodovia Raposo Tavares Km 572, B2-205, 19067-175, Presidente Prudente, SP, Brazil
| | - Matheus Z Gaspar
- Laboratory of Toxinology and Cardiovascular Research, Graduate Program in Health Sciences, University of Western São Paulo, Rodovia Raposo Tavares Km 572, B2-205, 19067-175, Presidente Prudente, SP, Brazil
| | - Luiz H B Quadros
- Laboratory of Toxinology and Cardiovascular Research, Graduate Program in Health Sciences, University of Western São Paulo, Rodovia Raposo Tavares Km 572, B2-205, 19067-175, Presidente Prudente, SP, Brazil
| | - Luís G G Lobo
- Laboratory of Toxinology and Cardiovascular Research, Graduate Program in Health Sciences, University of Western São Paulo, Rodovia Raposo Tavares Km 572, B2-205, 19067-175, Presidente Prudente, SP, Brazil
| | - Rogério Giuffrida
- Graduate Program in Animal Sciences, University of Western São Paulo, Rodovia Raposo Tavares Km 572, 19067-175, Presidente Prudente, SP, Brazil
| | - Cecília L Santarém
- Graduate Program in Animal Sciences, University of Western São Paulo, Rodovia Raposo Tavares Km 572, 19067-175, Presidente Prudente, SP, Brazil
| | - Elisangela O Silva
- Graduate Program in Animal Sciences, University of Western São Paulo, Rodovia Raposo Tavares Km 572, 19067-175, Presidente Prudente, SP, Brazil
| | - Juliana R Gerez
- Department of Histology, State University of Londrina (UEL), Rodovia Celso Garcia Cid Km 380, 86057-970, Londrina, PR, Brazil
| | - Nelson J Silva
- Graduate Program in Environmental Sciences and Health, School of Medical, Pharmaceutical and Biomedical Sciences, Pontifical Catholic University of Goiás (PUC-Goiás), 74605-140, Goiânia, GO, Brazil
| | - Stephen Hyslop
- Section of Pharmacology, Department of Translational Medicine, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, 13083-887, Campinas, SP, Brazil
| | - Bruno Lomonte
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, 11501, San José, Costa Rica.
| | - Rafael S Floriano
- Laboratory of Toxinology and Cardiovascular Research, Graduate Program in Health Sciences, University of Western São Paulo, Rodovia Raposo Tavares Km 572, B2-205, 19067-175, Presidente Prudente, SP, Brazil.
| |
Collapse
|
4
|
In Vivo Cardiotoxic Potential of Micrurus frontalis Venom. Cardiovasc Toxicol 2022; 22:181-190. [DOI: 10.1007/s12012-021-09713-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 12/13/2021] [Indexed: 11/26/2022]
|
5
|
Dobson JS, Harris RJ, Zdenek CN, Huynh T, Hodgson WC, Bosmans F, Fourmy R, Violette A, Fry BG. The Dragon's Paralysing Spell: Evidence of Sodium and Calcium Ion Channel Binding Neurotoxins in Helodermatid and Varanid Lizard Venoms. Toxins (Basel) 2021; 13:toxins13080549. [PMID: 34437420 PMCID: PMC8402328 DOI: 10.3390/toxins13080549] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 07/26/2021] [Accepted: 07/27/2021] [Indexed: 12/19/2022] Open
Abstract
Bites from helodermatid lizards can cause pain, paresthesia, paralysis, and tachycardia, as well as other symptoms consistent with neurotoxicity. Furthermore, in vitro studies have shown that Heloderma horridum venom inhibits ion flux and blocks the electrical stimulation of skeletal muscles. Helodermatids have long been considered the only venomous lizards, but a large body of robust evidence has demonstrated venom to be a basal trait of Anguimorpha. This clade includes varanid lizards, whose bites have been reported to cause anticoagulation, pain, and occasionally paralysis and tachycardia. Despite the evolutionary novelty of these lizard venoms, their neuromuscular targets have yet to be identified, even for the iconic helodermatid lizards. Therefore, to fill this knowledge gap, the venoms of three Heloderma species (H. exasperatum, H. horridum and H. suspectum) and two Varanus species (V. salvadorii and V. varius) were investigated using Gallus gallus chick biventer cervicis nerve–muscle preparations and biolayer interferometry assays for binding to mammalian ion channels. Incubation with Heloderma venoms caused the reduction in nerve-mediated muscle twitches post initial response of avian skeletal muscle tissue preparation assays suggesting voltage-gated sodium (NaV) channel binding. Congruent with the flaccid paralysis inducing blockage of electrical stimulation in the skeletal muscle preparations, the biolayer interferometry tests with Heloderma suspectum venom revealed binding to the S3–S4 loop within voltage-sensing domain IV of the skeletal muscle channel subtype, NaV1.4. Consistent with tachycardia reported in clinical cases, the venom also bound to voltage-sensing domain IV of the cardiac smooth muscle calcium channel, CaV1.2. While Varanus varius venom did not have discernable effects in the avian tissue preparation assay at the concentration tested, in the biointerferometry assay both V. varius and V. salvadorii bound to voltage-sensing domain IV of both NaV1.4 and CaV1.2, similar to H. suspectum venom. The ability of varanid venoms to bind to mammalian ion channels but not to the avian tissue preparation suggests prey-selective actions, as did the differential potency within the Heloderma venoms for avian versus mammalian pathophysiological targets. This study thus presents the detailed characterization of Heloderma venom ion channel neurotoxicity and offers the first evidence of varanid lizard venom neurotoxicity. In addition, the data not only provide information useful to understanding the clinical effects produced by envenomations, but also reveal their utility as physiological probes, and underscore the potential utility of neglected venomous lineages in the drug design and development pipeline.
Collapse
Affiliation(s)
- James S. Dobson
- Venom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia, QLD 4072, Australia; (J.S.D.); (R.J.H.); (C.N.Z.)
| | - Richard J. Harris
- Venom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia, QLD 4072, Australia; (J.S.D.); (R.J.H.); (C.N.Z.)
| | - Christina N. Zdenek
- Venom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia, QLD 4072, Australia; (J.S.D.); (R.J.H.); (C.N.Z.)
| | - Tam Huynh
- Department of Pharmacology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; (T.H.); (W.C.H.)
| | - Wayne C. Hodgson
- Department of Pharmacology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia; (T.H.); (W.C.H.)
| | - Frank Bosmans
- Department of Basic and Applied Medical Sciences, Ghent University, 9000 Ghent, Belgium;
| | - Rudy Fourmy
- Alphabiotoxine Laboratory sprl, Barberie 15, 7911 Montroeul-au-Bois, Belgium; (R.F.); (A.V.)
| | - Aude Violette
- Alphabiotoxine Laboratory sprl, Barberie 15, 7911 Montroeul-au-Bois, Belgium; (R.F.); (A.V.)
| | - Bryan G. Fry
- Venom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia, QLD 4072, Australia; (J.S.D.); (R.J.H.); (C.N.Z.)
- Correspondence: ; Tel.: +61-7-336-58515
| |
Collapse
|
6
|
Wu Y, Chen Z, Sigworth FJ, Canessa CM. Structure and analysis of nanobody binding to the human ASIC1a ion channel. eLife 2021; 10:e67115. [PMID: 34319232 PMCID: PMC8318589 DOI: 10.7554/elife.67115] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 07/13/2021] [Indexed: 11/13/2022] Open
Abstract
ASIC1a is a proton-gated sodium channel involved in modulation of pain, fear, addiction, and ischemia-induced neuronal injury. We report isolation and characterization of alpaca-derived nanobodies (Nbs) that specifically target human ASIC1a. Cryo-electron microscopy of the human ASIC1a channel at pH 7.4 in complex with one of these, Nb.C1, yielded a structure at 2.9 Å resolution. It is revealed that Nb.C1 binds to a site overlapping with that of the Texas coral snake toxin (MitTx1) and the black mamba venom Mambalgin-1; however, the Nb.C1-binding site does not overlap with that of the inhibitory tarantula toxin psalmotoxin-1 (PcTx1). Fusion of Nb.C1 with PcTx1 in a single polypeptide markedly enhances the potency of PcTx1, whereas competition of Nb.C1 and MitTx1 for binding reduces channel activation by the toxin. Thus, Nb.C1 is a molecular tool for biochemical and structural studies of hASIC1a; a potential antidote to the pain-inducing component of coral snake bite; and a candidate to potentiate PcTx1-mediated inhibition of hASIC1a in vivo for therapeutic applications.
Collapse
Affiliation(s)
- Yangyu Wu
- Basic Sciences Department, Tsinghua University School of MedicineBeijingChina
| | - Zhuyuan Chen
- Basic Sciences Department, Tsinghua University School of MedicineBeijingChina
| | - Fred J Sigworth
- Cellular and Molecular Physiology, Yale University School of MedicineNew HavenUnited States
| | - Cecilia M Canessa
- Basic Sciences Department, Tsinghua University School of MedicineBeijingChina
- Cellular and Molecular Physiology, Yale University School of MedicineNew HavenUnited States
| |
Collapse
|
7
|
Bénard-Valle M, Neri-Castro E, Elizalde-Morales N, Olvera-Rodríguez A, Strickland J, Acosta G, Alagón A. Protein composition and biochemical characterization of venom from Sonoran Coral Snakes (Micruroides euryxanthus). Biochimie 2021; 182:206-216. [PMID: 33485932 DOI: 10.1016/j.biochi.2021.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 01/05/2021] [Accepted: 01/06/2021] [Indexed: 11/16/2022]
Abstract
The elapid genus, Micruroides, is considered the sister clade of all New World coral snakes (Genus Micrurus), is monotypic, and is represented by Sonoran Coral Snakes, Micruroides euryxanthus. Coral snakes of the genus Micrurus have been reported to have venoms that are predominantly composed of phospholipases A2 (PLA2) or three finger toxins (3FTx), but the venoms of the genus Micruroides are almost completely unstudied. Here, we present the first description of the venom of M. euryxanthus including identification of some proteins as well as transcriptomic, and biological activity assays. The most abundant components within M. euryxanthus venom are 3FTxs (62.3%) and there was relatively low proportion of PLA2s (14.2%). The venom phenotype supports the hypothesis that the common ancestor of Micrurus and Micruroides had a 3FTx-dominated venom. Within the venom, there were two nearly identical α-neurotoxins (α-Ntx), one of which was designated Eurytoxin, that account for approximately 60% of the venom's lethality to mice. Eurytoxin was cloned, expressed in a soluble and active form, and used to produce rabbit hyperimmune serum. This allowed the analysis of its immunochemical properties, showing them to be different from the recombinant αNTx D.H., present in the venoms of some species of Micrurus. Finally, we observed that the commercial antivenom produced in Mexico for coral snake envenomation is unable to neutralize the lethality from M. euryxanthus venom. This work allowed the classification of Micruroides venom into the 3FTx-predominant group and identified the main components responsible for toxicity to mice.
Collapse
Affiliation(s)
- Melisa Bénard-Valle
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad # 2001, Colonia Chamilpa, CP: 62210, Cuernavaca, Morelos, Mexico
| | - Edgar Neri-Castro
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad # 2001, Colonia Chamilpa, CP: 62210, Cuernavaca, Morelos, Mexico
| | - Nicolás Elizalde-Morales
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad # 2001, Colonia Chamilpa, CP: 62210, Cuernavaca, Morelos, Mexico
| | - Alejandro Olvera-Rodríguez
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad # 2001, Colonia Chamilpa, CP: 62210, Cuernavaca, Morelos, Mexico
| | - Jason Strickland
- Department of Biological Sciences, Clemson University, Clemson, SC, 29632, USA; Department of Biology, University of South Alabama, Mobile, AL, 36688, USA
| | - Gerardo Acosta
- MIVIA. Museo Itinerante de Vida Animal, Hermosillo, Sonora, Mexico
| | - Alejandro Alagón
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad # 2001, Colonia Chamilpa, CP: 62210, Cuernavaca, Morelos, Mexico.
| |
Collapse
|
8
|
Titelbaum NV, Hughes MJ, Wilson JL. Myalgia as a Symptom of Envenomation by the Eastern Coral Snake, Micrurus Fulvius: A Case Report. Wilderness Environ Med 2020; 32:63-69. [PMID: 33309199 DOI: 10.1016/j.wem.2020.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 08/09/2020] [Accepted: 08/21/2020] [Indexed: 11/19/2022]
Abstract
We present the case of a patient who developed myalgia as the primary symptom of envenomation by the eastern coral snake, Micrurus fulvius. The patient was evaluated and treated in the emergency department. Physical examination did not demonstrate any neuromuscular abnormalities. On consultation with the poison control center, the patient's myalgia was determined to be an effect of envenomation, and 5 vials of North American coral snake antivenin were administered. The patient was admitted to the intensive care unit where his symptoms resolved. He was discharged the following day after remaining asymptomatic for 24 h.
Collapse
Affiliation(s)
- Nicholas V Titelbaum
- University of Central Florida, Orlando, FL; Ocala Regional Emergency Department, Ocala Regional Medical Center, Ocala, FL.
| | - Michael J Hughes
- University of Central Florida, Orlando, FL; Ocala Regional Emergency Department, Ocala Regional Medical Center, Ocala, FL
| | - James L Wilson
- Ocala Regional Emergency Department, Ocala Regional Medical Center, Ocala, FL
| |
Collapse
|
9
|
Dashevsky D, Bénard-Valle M, Neri-Castro E, Youngman NJ, Zdenek CN, Alagón A, Portes-Junior JA, Frank N, Fry BG. Anticoagulant Micrurus venoms: Targets and neutralization. Toxicol Lett 2020; 337:91-97. [PMID: 33197555 DOI: 10.1016/j.toxlet.2020.11.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 10/30/2020] [Accepted: 11/09/2020] [Indexed: 11/26/2022]
Abstract
Snakebite is a neglected tropical disease with a massive global burden of injury and death. The best current treatments, antivenoms, are plagued by a number of logistical issues that limit supply and access in remote or poor regions. We explore the anticoagulant properties of venoms from the genus Micrurus (coral snakes), which have been largely unstudied, as well as the effectiveness of antivenom and a small-molecule phospholipase inhibitor-varespladib-at counteracting these effects. Our in vitro results suggest that these venoms likely interfere with the formation or function of the prothrombinase complex. We find that the anticoagulant potency varies widely across the genus and is especially pronounced in M. laticollaris. This variation does not appear to correspond to previously described patterns regarding the relative expression of the three-finger toxin and phospholipase A2 (PLA2) toxin families within the venoms of this genus. The coral snake antivenom Coralmyn, is largely unable to ameliorate these effects except for M. ibiboboca. Varespladib on the other hand completely abolished the anticoagulant activity of every venom. This is consistent with the growing body of results showing that varespladib may be an effective treatment for a wide range of toxicity caused by PLA2 toxins from many different snake species. Varespladib is a particularly attractive candidate to help alleviate the burden of snakebite because it is an approved drug that possesses several logistical advantages over antivenom including temperature stability and oral availability.
Collapse
Affiliation(s)
- Daniel Dashevsky
- Toxin Evolution Lab, School of Biological Sciences, University of Queensland, St Lucia, QLD 4072 Australia; Australian National Insect Collection, Commonwealth Science and Industry Research Organization, Canberra, ACT 2601 Australia
| | - Melisa Bénard-Valle
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologa, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca, Morelos, 62210, Mexico
| | - Edgar Neri-Castro
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologa, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca, Morelos, 62210, Mexico
| | - Nicholas J Youngman
- Toxin Evolution Lab, School of Biological Sciences, University of Queensland, St Lucia, QLD 4072 Australia
| | - Christina N Zdenek
- Toxin Evolution Lab, School of Biological Sciences, University of Queensland, St Lucia, QLD 4072 Australia
| | - Alejandro Alagón
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologa, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca, Morelos, 62210, Mexico
| | - José A Portes-Junior
- Laboratório de Coleções Zoológicas, Instituto Butantan, São Paulo 05503-900, Brazil
| | | | - Bryan G Fry
- Toxin Evolution Lab, School of Biological Sciences, University of Queensland, St Lucia, QLD 4072 Australia.
| |
Collapse
|
10
|
Greene S, Ruha AM, Campleman S, Brent J, Wax P. Epidemiology, Clinical Features, and Management of Texas Coral Snake (Micrurus tener) Envenomations Reported to the North American Snakebite Registry. J Med Toxicol 2020; 17:51-56. [PMID: 32803694 DOI: 10.1007/s13181-020-00806-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 08/07/2020] [Accepted: 08/08/2020] [Indexed: 11/28/2022] Open
Abstract
INTRODUCTION Few of the 5000-8000 snakebites reported to poison control centers annually in the USA are attributed to coral snakes. This study describes Texas coral snake envenomations reported to the North American Snakebite Registry. METHODS All Texas coral snake envenomation cases reported to the registry were identified for the period from January 1, 2015, through December 31, 2019. Data reviewed for this study included details regarding the snake encounter, patient demographics, signs and symptoms, treatment, and outcomes. Descriptive statistics were used to report results. RESULTS Ten men and four nonpregnant women reported coral snake bites. The median patient age was 15.5 (range 5-72 years). There were 12 upper extremity bites and two bites to the lower extremity. The most common symptoms reported were paresthesias and pain. All subjects had paresthesias, often described as an "electric" sensation. Seven patients described them as painful. The most common clinical findings were erythema and swelling. No patient developed tissue damage, hematotoxicity, rhabdomyolysis, hypotension, weakness, or respiratory symptoms. Thirteen subjects were treated with opioids. Six patients were treated with antiemetics: three prophylactically and two for opioid-induced nausea. One patient developed nausea and non-bloody, nonbilious emesis within 1 hour of the bite, prior to receiving opioids. No patients were treated with antivenom. Antibiotics were not administered to any patient, and no infections were reported. CONCLUSIONS Envenomations from M. tener in Southeast Texas are characterized by painful paresthesias. Mild swelling and erythema are common. Neurotoxicity necessitating antivenom or mechanical ventilation did not occur.
Collapse
Affiliation(s)
- Spencer Greene
- Department of Emergency Medicine, Wright State University Boonshoft School of Medicine, Dayton, OH, USA. .,Unviersity of Texas Health Science Center Cizik School of Nursing, 6711 Stella Link Rd, Houston, TX, 77005, USA.
| | - Anne-Michelle Ruha
- Department of Medical Toxicology, Banner, University Medical Center Phoenix, Phoenix, AZ, USA
| | | | - Jeffrey Brent
- University of Colorado School of Medicine, Denver, CO, USA
| | - Paul Wax
- American College of Medical Toxicology, Phoenix, AZ, USA.,Department of Emergency Medicine, Division of Medical Toxicology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | | |
Collapse
|
11
|
Bénard-Valle M, Neri-Castro E, Yañez-Mendoza MF, Lomonte B, Olvera A, Zamudio F, Restano-Cassulini R, Possani LD, Jiménez-Ferrer E, Alagón A. Functional, proteomic and transcriptomic characterization of the venom from Micrurus browni browni: Identification of the first lethal multimeric neurotoxin in coral snake venom. J Proteomics 2020; 225:103863. [DOI: 10.1016/j.jprot.2020.103863] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 05/18/2020] [Accepted: 06/04/2020] [Indexed: 10/24/2022]
|
12
|
|
13
|
Sarmiento K, Rodríguez A, Quevedo-Buitrago W, Torres I, Ríos C, Ruíz L, Salazar J, Hidalgo-Martínez P, Diez H. Comparación de la eficacia, la seguridad y la farmacocinética de los antivenenos antiofídicos: revisión de literatura. UNIVERSITAS MÉDICA 2019. [DOI: 10.11144/javeriana.umed61-1.anti] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
En Colombia se presentan anualmente alrededor de 5000 casos de mordedura de serpiente y su tratamiento se basa en la neutralización con inmunoglobulinas completas purificadas, sin embargo, globalmente se utilizan antivenenos faboterápicos. Objetivo: Dar a conocer diferencias entre las generaciones de antivenenos, la importancia del veneno en la producción de anticuerpos, comparar aspectos farmacocinéticos y los efectos adversos en pacientes. Materiales Métodos: Se realizó una búsqueda de literatura en bases de datos utilizando combinaciones de los descriptores y términos Mesh, en inglés y español. Se cotejaron parámetros farmacocinéticos en estudios preclínicos y los efectos adversos en estudios clínicos. Resultados: Se encontraron diferencias debidas al tamaño de la fracción de la inmunoglobulina que la compone, así entre más pequeña es ésta, se observa mayor distribución a los tejidos y una vida media más corta, comparada con las moléculas más pesadas. Se encontraron estudios con disminución de efectos adversos con antivenenos faboterápicos
Collapse
|
14
|
Venomous Landmines: Clinical Implications of Extreme Coagulotoxic Diversification and Differential Neutralization by Antivenom of Venoms within the Viperid Snake Genus Bitis. Toxins (Basel) 2019; 11:toxins11070422. [PMID: 31331004 PMCID: PMC6669450 DOI: 10.3390/toxins11070422] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 07/15/2019] [Accepted: 07/16/2019] [Indexed: 12/29/2022] Open
Abstract
The genus Bitis comprises 17 snake species that inhabit Africa and the Arabian Peninsula. They are responsible for a significant proportion of snakebites in the region. The venoms of the two independent lineages of giant Bitis (B. arietans and again in the common ancestor of the clade consisting of B. gabonica, B. nasicornis, B. parviocula and B. rhinoceros) induce an array of debilitating effects including anticoagulation, hemorrhagic shock and cytotoxicity, whilst the dwarf species B. atropos is known to have strong neurotoxic effects. However, the venom effects of the other species within the genus have not been explored in detail. A series of coagulation assays were implemented to assess the coagulotoxic venom effects of fourteen species within the genus. This study identified procoagulant venom as the ancestral condition, retained only by the basal dwarf species B. worthingtoni, suggesting anticoagulant venom is a derived trait within the Bitis genus and has been secondarily amplified on at least four occasions. A wide range of anticoagulant mechanisms were identified, such as coagulant and destructive activities upon fibrinogen in both giant and dwarf Bitis and the action of inhibiting the prothrombinase complex, which is present in a clade of dwarf Bitis. Antivenom studies revealed that while the procoagulant effects of B. worthingtoni were poorly neutralized, and thus a cause for concern, the differential mechanisms of anticoagulation in other species were all well neutralized. Thus, this study concludes there is a wide range of coagulotoxic mechanisms which have evolved within the Bitis genus and that clinical management strategies are limited for the procoagulant effects of B. worthingtoni, but that anticoagulant effects of other species are readily treated by the South African polyvalent antivenom. These results therefore have direct, real-work implications for the treatment of envenomed patients.
Collapse
|
15
|
Neurotoxicity of Micrurus lemniscatus lemniscatus (South American coralsnake) venom in vertebrate neuromuscular preparations in vitro and neutralization by antivenom. Arch Toxicol 2019; 93:2065-2086. [PMID: 31123802 DOI: 10.1007/s00204-019-02476-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 05/08/2019] [Indexed: 10/26/2022]
Abstract
We investigated the effect of South American coralsnake (Micrurus lemniscatus lemniscatus) venom on neurotransmission in vertebrate nerve-muscle preparations in vitro. The venom (0.1-30 µg/ml) showed calcium-dependent PLA2 activity and caused irreversible neuromuscular blockade in chick biventer cervicis (BC) and mouse phrenic nerve-diaphragm (PND) preparations. In BC preparations, contractures to exogenous acetylcholine and carbachol (CCh), but not KCl, were abolished by venom concentrations ≥ 0.3 µg/ml; in PND preparations, the amplitude of the tetanic response was progressively attenuated, but with little tetanic fade. In low Ca2+ physiological solution, venom (10 µg/ml) caused neuromuscular blockade in PND preparations within ~ 10 min that was reversible by washing; the addition of Ca2+ immediately after the blockade temporarily restored the twitch responses, but did not prevent the progression to irreversible blockade. Venom (10 µg/ml) did not depolarize diaphragm muscle, prevent depolarization by CCh, or cause muscle contracture or histological damage. Venom (3 µg/ml) had a biphasic effect on the frequency of miniature end-plate potentials, but did not affect their amplitude; there was a progressive decrease in the amplitude of evoked end-plate potentials. The amplitude of compound action potentials in mouse sciatic nerve was unaffected by venom (10 µg/ml). Pre-incubation of venom with coralsnake antivenom (Instituto Butantan) at the recommended antivenom:venom ratio did not neutralize the neuromuscular blockade in PND preparations, but total neutralization was achieved with a tenfold greater volume of antivenom. The addition of antivenom after 50% and 80% blockade restored the twitch responses. These results show that M. lemniscatus lemniscatus venom causes potent, irreversible neuromuscular blockade, without myonecrosis. This blockade is apparently mediated by pre- and postsynaptic neurotoxins and can be reversed by coralsnake antivenom.
Collapse
|
16
|
New insights into the phylogeographic distribution of the 3FTx/PLA2 venom dichotomy across genus Micrurus in South America. J Proteomics 2019; 200:90-101. [DOI: 10.1016/j.jprot.2019.03.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 03/24/2019] [Accepted: 03/25/2019] [Indexed: 01/01/2023]
|
17
|
Castillo-Beltrán MC, Hurtado-Gómez JP, Corredor-Espinel V, Ruiz-Gómez FJ. A polyvalent coral snake antivenom with broad neutralization capacity. PLoS Negl Trop Dis 2019; 13:e0007250. [PMID: 30856180 PMCID: PMC6428337 DOI: 10.1371/journal.pntd.0007250] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 03/21/2019] [Accepted: 02/19/2019] [Indexed: 01/08/2023] Open
Abstract
Coral snakes of the genus Micrurus have a high diversity and wide distribution in the Americas. Despite envenomings by these animals being uncommon, accidents are often severe and may result in death. Producing an antivenom to treat these envenomings has been challenging since coral snakes are difficult to catch, produce small amounts of venom, and the antivenoms produced have shown limited cross neutralization. Here we present data of cross neutralization among monovalent antivenoms raised against M. dumerilii, M. isozonus, M. mipartitus and M. surinamensis and the development of a new polyvalent coral snake antivenom, resulting from the mix of monovalent antivenoms. Our results, show that this coral snake antivenom has high neutralizing potency and wide taxonomic coverage, constituting a possible alternative for a long sought Pan-American coral snake antivenom.
Collapse
Affiliation(s)
- María Carlina Castillo-Beltrán
- Grupo de Investigación en Animales Ponzoñosos y sus Venenos, Grupo de Producción y Desarrollo Tecnológico, Dirección de Producción, Instituto Nacional de Salud, Bogotá, Colombia
| | - Juan Pablo Hurtado-Gómez
- Grupo de Investigación en Animales Ponzoñosos y sus Venenos, Grupo de Producción y Desarrollo Tecnológico, Dirección de Producción, Instituto Nacional de Salud, Bogotá, Colombia
| | - Vladimir Corredor-Espinel
- Parasitology Laboratory, Department of Public Health, Faculty of Medicine, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Francisco Javier Ruiz-Gómez
- Grupo de Investigación en Animales Ponzoñosos y sus Venenos, Grupo de Producción y Desarrollo Tecnológico, Dirección de Producción, Instituto Nacional de Salud, Bogotá, Colombia
| |
Collapse
|
18
|
Paniagua D, Vergara I, Román R, Romero C, Benard-Valle M, Calderón A, Jiménez L, Bernas MJ, Witte MH, Boyer LV, Alagón A. Antivenom effect on lymphatic absorption and pharmacokinetics of coral snake venom using a large animal model. Clin Toxicol (Phila) 2019; 57:727-734. [PMID: 30773936 DOI: 10.1080/15563650.2018.1550199] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Context: Historically, administration and dosing of antivenom (AV) have been guided primarily by physician judgment because of incomplete understanding of the envenomation process. As demonstrated previously, lymphatic absorption plays a major role in the availability and pharmacokinetics (PK) of coral snake venom injected subcutaneously, which suggests that absorption from subcutaneous tissue is the limiting step for venom bioavailability, supporting the notion that the bite site is an ongoing venom depot. This feature may underlie the recurrence phenomena reported in viperid envenomation that appear to result from a mismatch between venom and AV PK. The role of lymphatic absorption in neutralization of venom by AV administered intravenously remains unclear. Methods: The effect of AV on systemic bioavailability and neutralization of Micrurus fulvius venom was assessed using a central lymph-cannulated sheep model. Venom was administered by subcutaneous injection in eight sheep, four with and four without thoracic duct cannulation and drainage. Two hours after venom injection, AV was administered intravenously. Venom and AV concentrations in serum and lymph were determined by ELISA assay from samples collected over a 6-h period and in tissues harvested post-mortem. Results: After AV injection, venom levels in serum fell immediately to undetectable with a subsequent increase in concentration attributable to non-toxic venom proteins. In lymph, AV became detectable 6 min after treatment; venom levels dropped concurrently but remained detectable 4 h later. Post-mortem samples from the venom injection site confirmed the presence of venom near the point of injection. Neither venom nor AV was detected at significant concentrations in major organs or contralateral skin. Conclusions: Intravenous AV immediately neutralizes venom in the bloodstream and can extravasate to neutralize venom absorbed by lymph but this neutralization seems to be slow and incomplete. Residual venom in the inoculation site demonstrates that this site functions as a depot where it is not neutralized by AV, which allows the venom to remain active with slow delivery to the bloodstream for ongoing systemic distribution.
Collapse
Affiliation(s)
- D Paniagua
- a Departamento de Biología Molecular y Bioprocesos , Instituto de Biotecnología Universidad Nacional Autónoma de México , Cuernavaca , México
| | - I Vergara
- b Department of Chemical and Biological Sciences, Sciences School , Universidad de las Américas Puebla , Cholula , México
| | - R Román
- a Departamento de Biología Molecular y Bioprocesos , Instituto de Biotecnología Universidad Nacional Autónoma de México , Cuernavaca , México
| | - C Romero
- c Centro Universitario UAEM Amecameca, Universidad Autónoma del Estado de México , Amecameca de Juarez , México
| | - M Benard-Valle
- a Departamento de Biología Molecular y Bioprocesos , Instituto de Biotecnología Universidad Nacional Autónoma de México , Cuernavaca , México
| | - A Calderón
- a Departamento de Biología Molecular y Bioprocesos , Instituto de Biotecnología Universidad Nacional Autónoma de México , Cuernavaca , México
| | - L Jiménez
- a Departamento de Biología Molecular y Bioprocesos , Instituto de Biotecnología Universidad Nacional Autónoma de México , Cuernavaca , México
| | - M J Bernas
- d Department of Medical Education , TCU and UNTHSC School of Medicine , Fort Worth , TX , USA.,e Department of Surgery , University of Arizona , Tucson , AZ , USA
| | - M H Witte
- e Department of Surgery , University of Arizona , Tucson , AZ , USA
| | - L V Boyer
- f Venom Immunochemistry, Pharmacology, and Emergency Response (VIPER) Institute, University of Arizona , Tucson , AZ , USA
| | - A Alagón
- a Departamento de Biología Molecular y Bioprocesos , Instituto de Biotecnología Universidad Nacional Autónoma de México , Cuernavaca , México
| |
Collapse
|
19
|
Preclinical assessment of the neutralizing efficacy of snake antivenoms in Latin America and the Caribbean: A review. Toxicon 2018; 146:138-150. [DOI: 10.1016/j.toxicon.2018.02.053] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 02/28/2018] [Indexed: 11/19/2022]
|
20
|
Fry BG. Snakebite: When the Human Touch Becomes a Bad Touch. Toxins (Basel) 2018; 10:E170. [PMID: 29690533 PMCID: PMC5923336 DOI: 10.3390/toxins10040170] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 04/19/2018] [Accepted: 04/20/2018] [Indexed: 01/08/2023] Open
Abstract
Many issues and complications in treating snakebite are a result of poor human social, economic and clinical intervention and management. As such, there is scope for significant improvements for reducing incidence and increasing patient outcomes. Snakes do not target humans as prey, but as our dwellings and farms expand ever farther and climate change increases snake activity periods, accidental encounters with snakes seeking water and prey increase drastically. Despite its long history, the snakebite crisis is neglected, ignored, underestimated and fundamentally misunderstood. Tens of thousands of lives are lost to snakebites each year and hundreds of thousands of people will survive with some form of permanent damage and reduced work capacity. These numbers are well recognized as being gross underestimations due to poor to non-existent record keeping in some of the most affected areas. These underestimations complicate achieving the proper recognition of snakebite’s socioeconomic impact and thus securing foreign aid to help alleviate this global crisis. Antivenoms are expensive and hospitals are few and far between, leaving people to seek help from traditional healers or use other forms of ineffective treatment. In some cases, cheaper, inappropriately manufactured antivenom from other regions is used despite no evidence for their efficacy, with often robust data demonstrating they are woefully ineffective in neutralizing many venoms for which they are marketed for. Inappropriate first-aid and treatments include cutting the wound, tourniquets, electrical shock, immersion in ice water, and use of ineffective herbal remedies by traditional healers. Even in the developed world, there are fundamental controversies including fasciotomy, pressure bandages, antivenom dosage, premedication such as adrenalin, and lack of antivenom for exotic snakebites in the pet trade. This review explores the myriad of human-origin factors that influence the trajectory of global snakebite causes and treatment failures and illustrate that snakebite is as much a sociological and economic problem as it is a medical one. Reducing the incidence and frequency of such controllable factors are therefore realistic targets to help alleviate the global snakebite burden as incremental improvements across several areas will have a strong cumulative effect.
Collapse
Affiliation(s)
- Bryan G Fry
- Venom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia, QLD 4072, Australia.
| |
Collapse
|
21
|
Ancient Diversification of Three-Finger Toxins in Micrurus Coral Snakes. J Mol Evol 2018; 86:58-67. [PMID: 29379986 DOI: 10.1007/s00239-017-9825-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 12/18/2017] [Indexed: 01/03/2023]
Abstract
Coral snakes, most notably the genus Micrurus, are the only terrestrial elapid snakes in the Americas. Elapid venoms are generally known for their potent neurotoxicity which is usually caused by Three-Finger Toxin (3FTx) proteins. These toxins can have a wide array of functions that have been characterized from the venom of other elapids. We examined publicly available sequences from Micrurus 3FTx to show that they belong to 8 monophyletic clades that diverged as deep in the 3FTx phylogenetic tree as the other clades with characterized functions. Functional residues from previously characterized clades of 3FTx are not well conserved in most of the Micrurus toxin clades. We also analyzed the patterns of selection on these toxins and find that they have been diversifying at different rates, with some having undergone extreme diversifying selection. This suggests that Micrurus 3FTx may contain a previously underappreciated functional diversity that has implications for the clinical outcomes of bite victims, the evolution and ecology of the genus, as well as the potential for biodiscovery efforts focusing on these toxins.
Collapse
|