COBRA VENOM

(Naja species)

MATTHEW MCBRIDE

TAXONOMY AND IDENTITY

• The common name “cobra” is applied to about 30 species of snake in 7 genera (Aspidelaps, Boulengerina, Hemachatus, Ophiophagus, Pseudohaje, Walterinnesia and Naja)

• The taxonomy of some species is unclear

• The term “cobra” is abbreviated from the Portuguese “cobra de capello”, which means “snake with hood” Hence, “cobra” refers to any species within the family Elapidae that can produce a hood when threatened.

• Cobras generally possess long and slender bodies with smooth scales

• Cobras vary in size from 2 meters in the Naja species to the King Cobra that can reach an average of 4 meters but can reach 5.5 meters (worlds largest venomous snake)

• Hollow fangs at the front of the maxilla (spitting cobras fangs modified)

FOCUS WILL BE ON THE NAJA SPECIES

• The genus Naja represents the typical cobra, which are perhaps what are commonly thought of as the archetypal cobras

• Naja comprises approximately 25 species (roughly) and is the most widespread

• This species has undergone several taxonomic revisions in recent years so sources vary in terms of actual number of species

• The Naja species range throughout Africa, Southern Asia

• All species in the genus Naja are capable of delivering a fatal bite in humans

• The Naja species typically have strong neurotoxic venom but may also have cytotoxic and cardiotoxic components as well

• Several Naja species are referred to as spitting cobras because of their ability to propel venom out their fangs and towards the eyes of predators

WHY FOCUS ON THE NAJA SPECIES?

• Wide geographic distribution in Africa and Southern Asia

• Large range in LD50’s (quantity of venom delivered ranges from 150mg to 350mg)

• Species contains some of the most venomous snakes worldwide

• Contain a unique spitting species

• Are one of if not the most recognized species of snake in the world (because of their characteristic hood)

• All species are able to raise up and appear large to predators

• Some surveys indicate fatalities around 25% of all bites (species identification leads to inaccuracies)

Pictures (top to bottom): Naja kaouthia, Naja nigricollis and Naja naja

WHAT IS VENOM

• Venom is a poison produced by glands a various snakes and injected through fangs into a victims flesh

• The composition of venom varies with different species

• In general snake venoms are largely a complex mixture of biologically active proteins and peptides

• Venoms contain a spectrum of biological activities: neurotoxic, myotoxic, cardiotoxic, coagulant, hemostatic, edema inducing, hemorrhagic and possible direct action on vital organs

• Highly efficient in immobilizing, killing and digesting its prey

FANGS AND VENOM GLAND (ELAPIDS) • Cobras are Proteroglyphous: meaning front

fanged

• The fangs are in the front part of the maxilla that is immobile

• The maxilla is typically short and have few teeth

• The fangs themselves are are up front and pointing downward with a hallow needle like structure

• The fangs acquire their venom from a venom gland behind the eyes in the temporal region

• The lumen of the gland is relatively small and the secretions are stored in cytoplasmic granules before reaching the lumen

• The expulsion of venom is by the contraction of specialized mandibular and temporal muscles

MAIN COMPONENTS/FUNCTIONS IN NAJA VENOM

• Neurotoxins (damage of nervous system and /or brain)

• Cardiotoxins (damage to the heart)

• Cytotoxic effects (cell destroying)

• Hemotoxins (destroy RBCs/disrupt blood clotting)

• Cobratoxin (binds to acetylcholine receptors on muscle cells)

• Phospholipases (hydrolyzes phospholipids)

• Phosphoesterases (cutting oxygen loose from ribose or desoxyribose)

• Acetylcholinesterase (hydrolyzes acetylcholine)

• L-amino-acid-oxidase (changes amino acids)

• Hyaluronidase (enhances diffusion of venom by breaking down connective tissue)

NEUROTOXIN MECHANISM (COMMON MECHANISM AMONG NAJA SPECIES)

• Alpha-cobratoxin is a nicotinic acetylcholine receptor antagonist (short chain alpha-neurotoxin)

• The cobratoxin binds to ligand-binding subunits in the postsynaptic membrane receptor (red v on diagram)

• Thus, preventing the binding of acetylcholine and prohibiting it from turning its chemical signal into an electric one

• The site of this mechanism is taking place at the synaptic cleft of the neuromuscular junction

• Final result of this can lead to death by respiratory paralysis

NEUROTOXIN MECHANISM CONTINUED(MORE SPECIFICALLY)

• Alpha-neurotoxins are largely found in the Elapidae family (cobra examples Naja atra and Naja siamensis)

• There are short and long alpha-neurotoxins

• The alpha-neurotoxin mechanism specifically is a muscular-type nicotinic acetylcholine receptor (nAChR), it’s a ligand-gated ion channel on the postsynaptic fold of the neuromuscular junction with specialized subunits

• Upon binding to the nAChR, the neurotoxin prevents binding the normal ligand acetylcholine and ion flow

• This leads to paralysis and ultimately death

PHOSPHOLIPASE (A2)

• The majority of snake venom contains phospholipase

• Hydrolyze free phospholipids and those bound to membranes (into fatty acids and lysophospholipids)

• Phospholipase A2 is the most common

• Phospholipase A2 affects several physiological systems depending on the type of hydrolyzed phospholipids, haemostasis, neuromuscular transmission, and inflammatory reaction

PHOSPHOESTERASES (PHOSPHODIESTERASE)• The endonucleases hydrolyze the nucleic

acids (DNA/RNA) at the bonds between the base pairs

• The exonucleases attack the base at the end of the nucleic chain

• The phosphodiesterases cut the link removing the oxygen from position 3’ of the ribose or the deoxyribose, separating them from the phosphorus

• The 5’ nucleotidase produces a similar cut but at the level of the bond 5’ between the ribose or the desoxyribose and the phosphor

• Functions to interfere with prey’s cardiac system by mainly lowering the preys blood pressure

L-AMINO-ACID-OXIDASE• The enzyme causes the des-amination and

then the oxidation of the amino acids, which are transformed into alpha-cetonic acid

• The clinical and toxicological effects are negligible, it represents less than 1% of the total toxicity of the venom (which explains its low concentration in the venom)

• The interesting fact about this enzyme is that flavin-adenin-dinucleotide group that is attached to the enzyme is what gives the venom its yellow color

• This component also has a anticoagulant, apoptotic-inducing, platelet aggregation-inducing and inhibiting properties

• Interestingly, this component is of biomedical interest because of its antimicrobial and anti-HIV activities

HYALURONIDASE

• This component of venom is valuable because it is responsible for disrupting the cohesion of connective tissue that allows venom to spread after a bite has occurred

• This enzyme hydrolyzes hyaluronic acid or the sulfate chondroitin

• Diffusion of toxins from bite site into blood is for successful envenomation and hyaluronidase allows this to occur

• Degradation of hyaluronic acid in the extracellular matrix is key to diffusion

• Increases potency of other toxins and destruction of local tissue

• Contributes to inflammation, tissue damage and spreading

UNIQUE NAJA SPECIES (SPITTING COBRAS)

• Some examples of spitting cobras: Naja pallida, Naja mossambica, Naja nigrcollis and Naja siamensis

• These species are able to eject venom out of their fangs as a defense response

• The muscles of the venom sac contract and force the venom out

• A combination of venom sac muscles and air exhaled from lungs provides the force

• These snakes are able to spray up to 10ft.

• Irrigation with water to venom from eyes prevents any permanent damage

• Venom in the eyes of victims without irrigation will result in chemosis and eventually blindness

Picture: Naja nigrcollis

COMPARISON OF VENOM STRENGTH (INTRAVENOUS LD-50’S)

4 highly ranked dangerous snakes

• LD-50 (mg/kg)---0.01---Eastern brown snake

• LD-50 (mg/kg)---0.071---Boomslang snake

• LD-50 (mg/kg)---0.25---Black mamba

• LD-50 (mg/kg)---1.5---Eastern green mamba

COMPARISON OF VENOM STRENGTH(INTRAVENOUS LD50’S)

5 species of Naja cobra

• LD-50 (mg/kg)---0.28---Black forest cobra (Naja melanoleuca)

• LD-50 (mg/kg)---0.34---Chinese cobra (Naja atra)

• LD-50 (mg/kg)---0.35---Spectacled cobra (Naja naja)

• LD-50 (mg/kg)---0.37---Monocled cobra (Naja kaouthia)

• LD-50 (mg/kg)---0.42)---Egyptian cobra (Naja haje)

WHAT TO DO WHEN A BITE OCCURS (BEST CASE SCENARIO)

• 1) Note the snakes appearance

-Be ready to describe the snake to

emergency staff

• 2) Protect the person (While waiting for medical help)

-Move the person beyond striking

distance

-Have the person lie down with wound

below the heart

-Keep the person still to keep the

venom from spreading

-Cover the wound with loose, sterile

bandage

Don’t: -cut a bite wound -attempt to suck out venom -apply tourniquet, ice, water -give alcohol or caffeine

TREATMENT: ANTI-VENOM

• Venom composition and its corresponding toxicity can vary among among cobras from the same species and even from the same litter. (even over its lifetime)

• This makes cobra venom truly unique and correct treatment is needed to ensure a successful recovery

• Ant-venom is created using venom from specific species of snake depending on the bite encountered and is then diluted to be injected into horses, sheep or goats

• After the injection of diluted venom the animal (horse, sheep or goat) will produce antibodies against the active components and is harvested from the animals blood

ANTI-VENOM TREATMENT CONTINUED

• Anti-venoms can be classified as either monovalent or polyvalent

• Monovalent anti-venom are effective against a certain species

• Polyvalent anti-venom are effective against a range of species

• Polyvalent have been known to be less effective and cause allergic reactions

• Monovalent anti-venoms are ideal but in various regions of the world where several dangerous cobras (or other species) are located close to one another and do not cause a distinctive clinical syndrome its difficult and expensive to effectively treat patients with it

• This is one of the numerous problems cobras can present and the public heath aspects of these snakes need to be highlighted and addressed

VENOM FOR MEDICAL PURPOSES• Venoms may hold the key to a whole host of scientific

avenues of disease

• Research has shown natural compounds in snake venom may prevent growth of cancerous tumors

• Snake venoms alter biological functions and researchers feel there is a lot of potential to be exploited

• The king cobra is a highly venomous snake and can deliver enough neurotoxin in a single bite to kill 20 people but shows promise in the field of medical research

• The king cobra has been studied for treating pain, cancers, autoimmune and neurological disorders

• Researchers have definitively proven that cobra venom contains components that control pain and inflammation

• Work in China has also focused on cobra venom for possible uses in drug addiction

• A lot of work still needs to be done but it looks promising thus far

PUBLIC HEATH ASPECTS TO BITES

• Snakebites in general are a serious medical problem world wide

• Various estimates show that 15,000- 20,000 people die annually in India due to snake envenomation

• The Naja species itself represents a major heath concern

• For example, Naja kaouthia is present in much of South Asia and causes the highest number of deaths due to snake envenomation Thailand

• Another good example is this species in India and even know the venom is well characterized there are no reports on the composition of this species venom in India

• This is of great importance because pathogenesis developing after a bite is dependent on the qualitative composition of the venom and also on the quantitative distribution of different components in a particular venom

• This limits how to handle and treat patients after a bite

PUBLIC HEALTH CONCERNS CONTINUED

• The World Health Organization estimates that at least 421,000 envenomings and 20,000 deaths occur worldwide from snakebites each year

• However, the highest rates are in South Asia, Southeast Asia and sub-Saharan Africa

• Poorer and rural farming communities are at the greatest risk

• Many victims are not able to reach medical facilities or reach it to late and have to deal with the physical disabilities due to local tissue necrosis

• The major groups contributing to problem is the elapids (cobras, kraits and mambas)

• Envenomation following snakebites, is largely a neglected threat to public health

• Training of heath staff is encouraged knowing the negative outcomes but its usually neglected

• Strong action is needed to ensure supplies and quality heath care providers to effectly deal with this problem

• Without this severe disabilities will continue, pain to families and death tolls will rise

RESULTS

• The Naja cobras are a diverse and dangerous group of snakes found mainly throughout Africa and Southern Asia

• They have a unique physical appearance and some special characteristics such as the spitting cobra(s) that are able to spit venom in the eyes of their prey/threats

• Their venom consist of numerous toxins that are focus mainly on the nervous system

• Cobras also have numerous other toxic mechanisms that are highly effective in weakening and killing their prey

• The lethal nature of their venom is close in comparison to some of the most deadly snakes on the planet

RESULTS

• Getting bit is obviously not desirable but in its occurrence its necessary to have the correct actions (try to remember the snakes appearance, keeping the victim still, don’t try to suck the venom out, ect)

• Anti-venom production results from the development of antibodies

• Monovalent and polyvalent anti-venoms are useful but do have limitations

• Cobras can have a devastating effect on various rural farming areas without efficient medical care

• High death rates and physical disabilities are shown in these rural areas

• Cobra bites and other venomous snake bites are relatively neglected and are proven by the high death/disability rates

• A need for trained medical professions/facilities are needed in rural areas for the statistics to change

CONCLUSION

• The diverse nature of cobras are fascinating yet pose many problems because of their complexity

• The classification of species is still changing and shows how difficult it is to find consistence's within them

• Developing a clear and accurate evolution of cobras will help protect them and aid in the treatment of bite victims

• Understanding mechanisms associated with venom components provides useful information for treatment and research

• The vast number of mechanism involved in venom physiology requires a lot of future research to better understand how to treat and protect people from its harmful effects

CONCLUSION

• Venomous snakes in general offer great opportunities to further the understanding of venom and how to treat bites

• A good base of information has been established and will aid in advancing knowledge

• Research is happening on how to use venom to treat various conditions (including drug addiction)

• The possibility of future cures is a major positive going forward

• Unfortunately, the complexity of venom makes the process slower than one would like

• The various rural areas that contain these snakes need to have this information and treatment much sooner because they face the greatest threat

• Awareness and concern is another major factor that needs to be addressed because it is not receiving near the amount of attention it deserves when examining the statistics

LITERATURE CITED

• http://www.cobras.org

• http://animals.nationalgeographic.com/animals/reptiles/cobras/

• http://www.venomoussnakes.net/cobrasnake.htm

• http://www.buzzle.com/articles/cobra-snake-facts.html

• http://apps.who.int/bloodproducts/snakeantivenoms/database/

• http://www.engin.umich.edu/~cre/web_mod/cobra/avenom.htm

• http://snakevenom.net/2010/01/what-is-snake-venom/

• http://emedicine.medscape.com/article/771918-treatment

• Chippaux, Jean Philippe. Snake Venoms: Envenomations. Malabar: Krieger, 2006.

• Martin, James. The Spitting Cobras of Africa. Bloomington: Capstone, 1995.

• McDonald, Mary Ann. Cobras. Mankato: Child’s Worlds, 1996.

• Russell, Findlay. Snake Venom Poisoning. New York: Scholium, 1983.