Venomous Snakes

Desiderio BritoDanielle Mascarenas

Joshua Thurgood

What is Venom?• Venom is defined as a

poisonous matter normally secreted by some animals (such as snakes, scorpions, or bees) and transmitted to prey or an enemy chiefly by biting or stinging; broadly: material that is poisonous. (Merriam-Webster, 2015)

• Venom is generally a compound formed by a mixture of toxins to be used on a broad range of targets with various effects.

Why we chose venomous snakes?

We chose to do our project on venomous snakes because during a lecture Professor Toolson mentioned “dry bites” and this made us realize that there is a lot we do not know about snakes and the way they transmit their venom. As we researched more in to the topic of snakes and snake venom we learned the diverse mechanisms that snakes use to distribute their venom and also how diverse the population of venomous snakes are right here in New Mexico.

Where is snake venom produced?

• There is a fairly large amount of debate as to the history and evolution of snake’s ability to produce venom, but one of the leading theories is the Toxicofera theory.

• Developed by Bryan G. Fry, the Toxicofera theory postulates that in snakes, and other reptilian species, venom systems arose as a single novel mutation over 100 million years ago.

• Through DNA analysis Fry discovered that a majority of the proteins and enzymes that make up snake venom closely resemble substances found in various other parts of snakes’ bodies. Eventually these substances became expressed in the salivary glands and eventually were specialized to become the venom that expresses itself today.

Heterodon nasicus• Commonly known as the western

hognose snake, this snake was not considered to be toxic until 1985 when Michael A. Morris published an article chronicling his experience with a bite from this snake.

• Belonging to the family Colubridae most members of this family are nonvenomous or mostly harmless to humans but there are a few species whose venom can be fatal.

• Colubrids envenomate their prey using (Opistoglyphous) rear grooved fixed fangs generally requiring multiple bites in order to transfer a sufficient amount of venom.

H. Nasicus Venom

• The venom secreted from this species of snakes was shown to contain an azocaseinase in the form of metalloproteases which work by degrading the extracellular matrix and coagulation proteins leading to increased bleeding at the site of the bite and phosphodiesterase which are believed to play a role in the disruption of ADP- and cAMP-mediated events.

Mechanism of Metalloproteases

• Metalloproteases in the body normally play a role in cell growth and proliferation, maintenance of the extracellular membrane, synaptogenesis, and angiogenesis. Mutant forms of these metalloproteases can lead to over activation of cell growth and are thought to be involved in tumor growth and metastasis.

• Snake venom metalloproteases (SVMP) are hyperactive. They work by degrading the extracellular matrix (especially in endothelial cells) and lysing cell surface proteins and coagulation proteins. This proteolytic activity results in local lesions and hemorrhaging. Hemorrhaging can lead to delayed muscle regeneration through inhibition of angiogenesis.

Micruroides euryxanthus

• Commonly known as the western (or Sonoran) coral snake, these are found in the southwestern United States from central Arizona and southwestern New Mexico southward in to Mexico.

• Belonging to the Elapidae family of snakes, all members of this family are venomous.

• Elapidae feature enlarged forward grooved fangs (proteroglyphous) through which they inject their venom.

M. euryxanthus Venom• Coral snakes have a poorly

developed system for venom delivery, requiring a chewing action to inject the venom much like H. nasicus.

• But the difference between these two species is that M. euryxanthus has teeth in the front of the mouth used to deliver the venom whereas H. nasicus has teeth at the rear of the mouth used to deliver venom.

• Coral snake venom is primarily neurotoxic with little local reaction or pain at the site of the bite.

• The net effect of the toxin is a curare like syndrome.

• Because of their primitive method of venom delivery most of the bites (between 60-98%) are non-envenomating.

• Approximately 4-5mg of venom is a lethal dose to humans.

M. euryxanthus Venom 2• Several neurotoxins may be involved in combination in coral

snake venom. The venom acts postsynaptically, preventing action potential propagation at the neuromuscular junction by binding to ACh receptors. The venom induces central nervous system depression, muscle paralysis, vasomotor instability, and respiratory arrest.

• In canine victims there have been reports of the venom causing hemolysis with severe anemia and marked hemoglobinuria. The cause of the red blood cell destruction is poorly understood, although it is speculated that it is because of the effects of phospholipase A and its interaction with red blood cell membranes.

M. Euryxanthus Treatment

• In the United States in 2006, Wyeth Pharmaceuticals released a statement saying that it would no longer produce North American Coral Snake Anti-venom (NACSA) which was used to treat M. fulvius (eastern coral snake) envenomation. In lab tests on female lab rats it was shown that NACSA was unable to treat the envenomation of M. tener (Texas Coral Snake).

• In a study to find a replacement anti-venom to be used in the United States it was found that Coralmyn, produced by a Mexican pharmaceutical company Bioclon, was a viable anti-venom able to treat both M. tener and M. fulvius venom.

• M. euryxanthus is generally believed to be rather innocuous and bites tend to be extremely rare in the species most often found in New Mexico.

NACSA• A polyclonal (secreted from multiple cells) immunoglobulin G (IgG)

antivenom• Inoculated in equine using M. fulvius venom.• Can cause adverse effects such as anaphylaxis• Takes up to 45 minutes to take effect.• ED50= 10mL neutralizes 250 LD50 doses of venom (approximately 5.5mL)

Coralmyn• A polyclonal fragment antigen-binding ((Fab’)2) antivenom• Inoculated in equine using Micururus nigrocinctus nigrocinctus (black-

banded coral snake) venom.• Takes effect immediately.

• ED50= 5mL neutralizes 450 LD50 doses of venom (approximately 5.5mL)

Rattlesnakes

• Part of the Crotalinae (Pit Viper) subfamily of snakes

• There are 32 known species which are all native to the North and South Americas

Venom

• All Rattlesnake species use hemotoxic venom• Uses bloodstream to destroy tissue

and to cause swelling and internal bleeding

• Some species also use a combination of hemotoxins and neurotoxins in their venom• Neurotoxins cause paralysis

Venom

• Rattlesnake species possess hinged fangs

• They can retract these fangs when not in use, retracting them against there palate

• These fangs are connected via ducts to poison glands

• This gives them better control of the amount of venom used in a “bite”

Venom

• Rattlesnake toxins also show geographic variance• Crotalus scutulatus• Crotalus atrox

Crotalus Scutulatus

• Mojave Rattlesnake• Southwestern United States and Central

Mexico• Uses a powerful neurotoxin in its venom

• One of the most deadly venoms in the United States

Crotalus Scutulatus

• The neurotoxin in Crotalus Scutulatus venom is known as Mojave Toxin• Made up of two subunits

• A phospholipase A2• An acidic peptide

• They are not significantly toxic alone but become extremely toxic when together

Crotalus Scutulatus

• Crotalus Scutulatus venom attacks the nervous system

• Venom Effects:• Visual abnormalities• Difficulties swallowing and

talking• Muscle Weakness• Difficulty breathing

Mojave Toxin Mechanism

• The effects of the Mojave Toxin are presynaptic• Gated calcium channels are inhibited through

phospholipase activity• Action Potential generation is stopped• Causes paralysis of muscle

• Explains many effects such as muscle weakness, difficulties breathing, etc.

Treatment

• Treatment for the envenomation by the Mojave Rattlesnake is the use of antivenom

• CroFab antivenom is used specifically• Crofab uses Mojave

Rattlesnake venom so it is used almost uniformly to treat rattlesnake bites

Crotolus Atrox

• Western Diamondback Rattlesnake• Found across most of the Southern United

States and Northern Mexico• Mixture of toxins in venom, but primarily

hemotoxic• Also contains some myotoxins and

cytotoxins

Crotolus Atrox

• Crotolus Atrox venom contains many proteolytic enzymes• These break done proteins

including structural proteins• Leads to tissue damage and

death• Also contains zinc

metalloproteinases• Hemorrhagic component • A protein that coordinates with

zinc ions• Also reduces skeletal muscle

regeneration

Crotolus Atrox

• Local Effects• Pain • Internal Bleeding• Swelling• Muscle Damage• Bruising• Tissue Death

• Systemic Effects• Headache• Nausea • Vomiting• Abdominal Pain• Diarrhea• Dizziness

Crotolus Atrox

• Most damage done by Crotolus Atrox venom is due to hemorrhaging

• The action of metal ions coordinating with proteins (metalloproteinases) causes severe bleeding and tissue damage

Treatment

• Treatment of Crotolus Atrox envenomation is also the use of the antivenom CroFab• Crofab is made from the toxins of several snakes from the subfamily

Crotalinae• Counteracts the effects of envenomation of many rattlesnake species

• What is it: Snake Venom• Where it comes from: Mutated salivary glands• What it does: There are a number of different toxins

that come in to play across the different species of snakes. They generally show hemotoxic and neurotoxic effects leading to swelling at the bite site and increased bleeding (hemotoxic effect) and in some more powerful venoms they can cause paralysis (neurotoxic effect) and even death.

Conclusion

• How it is delivered: depending on the family that the snake belongs to will tell you a lot about how snakes envenomate their prey. – Colubrids have fixed fangs in the back of the mouth with

long venom glands that run below the teeth, but often the venom is rather weak.

– Elapids have fixed fangs in the front of the mouth and large venom glands above the fangs.

– Crotalus have hinged fangs that they can control and this muscular control of the fangs makes them better at controlling how much venom they release in their bites. Generally members of this family have very powerful venom.

Conclusion

• Antivenoms are generally created from the venom that they are meant to treat.

• The development of complex venom distribution systems have made snakes excellent hunters that are to be taken with caution at all times.

• Snake venom is a very diverse subject as snakes vary greatly in what they use venom for. Uses range from offensive use to hunt prey, defensive uses to warn predators that they are dangerous, and predigestion of prey.– It should be noted that Western Diamondback venom

causes tissue necrosis but it is not used in predigestion of its prey.

Conclusion

References• Biardi, J. E., and Coss, R.G. 2011. Rock Squirrel (Spermophilus Variegatus) Blood Sera

Affects Proteolytic and Hemolytic Activities of Rattlesnake Venoms. Toxicon. Vol. 57, No. 2: 323-31.

• Borkow, G., Marco, D., Ovadia, M. 2008. Isolation and Partial Characterization of an Antiviral Proteolytic Fraction from the Venom of Echis Carinatus Sochureki. The Open Biology Journal. Vol. 1: 21-26.

• Cameron, J. The danger of scorpion sting. Retrieved April 8, 2015 from http://www.thecameronteam.com/the-danger-of-scorpion-sting/.

• Carstairs, SD, AA Kreshak, and DA Tanen. 2013. Crotaline Fab Antivenom Reverses Platelet Dysfunction Induced by Crotalus Scutulatus Venom: an in Vitro Study. Academic Emergency Medicine: Official Journal of the Society for Academic Emergency Medicine. Vol. 20, No. 5: 522-5.

• Chang, C., and Werb, Z. The Many Faces of Metalloproteases: Cell Growth, Invasion, Angiogenesis and Metastasis. Trends in Cell Biology. U.S. National Library of Medicine.

• Dagda, R.K, B Zhang, W Welch, S.E Gasanov, S.E Gasanov, W Welch, and E.D Rael. 2014. Molecular Models of the Mojave Rattlesnake (crotalus Scutulatus Scutulatus) Venom Metalloproteinases Reveal a Structural Basis for Differences in Hemorrhagic Activities. Journal of Biological Physics. Vol. 40, No. 2: 193-216.

• Fox, Jay W, and Jon B. Bjarnason. 1983. New Proteases from Crotalus Atrox Venom. Toxin Reviews. Vol. 2 No. 2: 161-204

• Fox, JW, R Campbell, L Beggerly, and JB Bjarnason. 1986. Substrate Specificities and Inhibition of Two Hemorrhagic Zinc Proteases Ht-C and Ht-D from Crotalus Atrox Venom. European Journal of Biochemistry / Febs. Vol. 156, No. 1: 65-72.

• Fry, B.G., Vidal, N., van der Weerd, L., Kochva, E., Renjifo, C. 2009. Evolution and diversification of the Toxicofera reptile venom system. Journal of Proteomics. Vol. 72, No. 2: 127-136.

• Fry, B.G., Casewell, N.R., Wuster, W., Vidal, N., Young, B., Jackson, T.N.W. 2012. The structural and functional diversification of the Toxicofera reptile venom system. Toxicon. Vol. 60, No. 4: 434-448.

• Gray, R. Bee sting venom could provide treatment for arthritis. Retrieved April 8, 2015 from http://www.telegraph.co.uk/news/science/science-news/7856017/Bee-sting-venom-could-provide-treatment-for-arthritis.html.

• Hill, R.E., Mackessy, S.P. 2000. Characterization of venom (Duvernoy’s secretion) from twelve species of colubrid snakes and partial sequence of four venom proteins. Toxicon. Vol. 38, No. 12: 1663-1687.

• Peterson, M. E. 2006. Snake Bite: Coral Snakes. Clinical Techniques in Small Animal Practice. Vol. 21, No. 4: 183-86.

References

• Ramos, O.H.P, and H.S. Selistre-De-Araujo. 2006. Snake Venom Metalloproteases — Structure and Function of Catalytic and Disintegrin Domains. Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology. Vol. 142, No. 3-4: 328-46.

• Sánchez, E. E., Lopez-Johnston, J.C., Rodríguez-Acosta, A., and Pérez, J.C. 2008. Neutralization of Two North American Coral Snake Venoms with United States and Mexican Antivenoms. Toxicon Vol. 51, No. 2: 297-303.

• Wassif, C., Cheek, D., Belas, R. 1995. Molecular Analysis of a Metalloprotease from Proteus mirabili. Journal of Bacteriology. Vol. 177, No. 20: 5790-5798.

• http://bib.ge/reptiles/open.php?id=1660 • http://www.dailymail.co.uk/news/article-2344107/Boy-11-bitten-eastern-diamondback-rattle

snake-survives-given-record-EIGHTY-vials-anti-venom.html

• http://www.madrean.org/symbfauna/imagelib/photographers.php?phuid=28&imgcnt=182&lstart=100&lnum=100

• http://www.popsci.com/scitech/article/2008-03/evolution%E2%80%99s-most-effective-killer-snake-venom

References