| Toxin |
|
Toxin activity type/ Functional target |
Clinical effects |
Source |
|
Neurotoxin
|
Short-chain neurotoxins
|
Post-synaptic; high affinity to skeletal and Torpedo nicotinic acetylcholine receptors (nAChR); bind to neuronal a7 nAChR with lower affinity or none.
|
Flaccid paralysis; Often reversal with antivenom therapy
|
Elapids and Hydrophids (Cobras, Sea snakes, Kraits, Australian Elapids)
|
|
|
Long-chain neurotoxins
|
Post-synaptic; comparatively higher affinity towards neuronal a7 nAChR than the skeletal receptors.
|
Flaccid paralysis; Often reversal with antivenom therapy
|
Elapids and Hydrophids (Cobras, Sea snakes, Kraits, Australian Elapids)
|
|
|
Weak neurotoxins
|
Post-synaptic; weak affinity to both the skeletal and neuronal nAChRs (nicotinic acetylcholine receptors)
|
Flaccid paralysis; Often reversal with antivenom therapy
|
Elapids (Cobras, Kraits, Australian Elapids)
|
|
|
Taipoxin
|
Presynaptic; binds specifically to neuronal plasma membranes especially at the neuromuscular junction.
|
Flaccid paralysis; Resistant to late antivenom therapy
|
Australian Elapid (Taipan)
|
|
|
β -Bungarotoxins
|
Presynaptic; presynaptic voltage dependent K+ channel
|
Flaccid paralysis
Resistant to late antivenom therapy
|
Elapids (Kraits)
|
|
|
Muscarinic toxins
|
Anticholinesterase;specific to mAChR (muscarinic acetylcholine receptor)subtype and bind with high affinity
|
Flaccid paralysis; Fasciculation
|
Elapids (Mamba, Kraits and Cobras)
|
|
|
Dendrotoxins; , toxins I and K
|
Inhibit neurotransmissions by blocking the exchange of positive and negative ions across the neuronal membrane lead to no nerve impulse, thereby paralysing the nerves.
|
Nerve paralysis
|
Elapids (Mambas)
|
|
Cardiotoxin
|
Cardiotoxin-3 (CTX-3)
|
They bind to particular sites on the surface of muscle cells and cause depolarisation ==> the toxin prevents muscle contraction. These toxins may cause the heart to beat irregularly or stop beating, causing death.
|
Direct cardiotoxicity
|
Mambas, and some Cobra species
|
|
|
Three-finger toxins (3FTx)
|
Rapid immobilization of prey, paralysis, death
|
|
Colubridae, Elapidae
|
|
Myotoxin
|
Myotoxin-a, crotamine
|
Myonecrosis, analgesia, immobilize prey
|
Systemic skeletal muscle damage
|
Viperidae
|
|
Haemotoxins
|
Haemostatic system toxins
|
Affects the blood and organs, causing a breakdown or inflammation in the body
|
Interfere with normal haemostasis, causing either bleeding or thrombosis
|
Most Vipers and many Cobra species
|
|
|
Haemorrhagins; Phospholipase A2, mucrotoxinA, hemorrhagic toxins a, b, c..., HT1, HT2
|
|
Damage vascular wall, causing bleeding
|
Most Vipers and many Cobra species
|
|
Nephrotoxins
|
|
|
Direct renal damage
|
|
|
|
Acetylcholinesterases (AChE)
|
Believed to cause tetanic paralysis
|
|
Colubridae, Elapidae
|
|
|
Hyaluronidases
|
Increase interstitial fluidity, aiding the dissemination of venom from the bite site
|
|
Elapidae, Viperidae
|
|
|
Bradykinin-potentiating peptides (BPP)
|
Pain, hypotension, immobilize prey
|
|
Viperidae
|
|
|
Phosphodiesterases (PDE)
|
Believed to cause hypotension, shock
|
|
Colubridae, Elapidae, Viperidae
|
|
|
Prothrombin activators
|
Disseminated intravascular coagulation (DIC: small clots form throughout body, leading to uncontrolled bleeding), which can be fatal
|
|
Elapidae
|
|
|
Serine proteases
|
Hemostasis disruption, hypotension, immobilize prey
|
|
Colubridae, Viperidae
|
|
Cytotoxin
(Enzymes)
|
Metalloproteases (MP),
|
Apoptosis induction
|
Hemorrhage, myonecrosis, believed to predigest prey
|
Atractaspididae, Colubridae, Elapidae, Viperidae
|
|
Disintegrins
|
RGD motif-dependent integrins, leukocyte integrin-binding disintegrins, a1β1 integrin-bindingdisintegrins
|
Inhibit platelet activity, promote hemorrhaging
|
Antiangiogenesis
|
Viperidae
|
|
|
L-amino acid oxidases (LAAOs)
|
Free radical generation, apoptosis induction
|
Cell damage/apoptosis
|
Elapidae, Viperidae
|
|
|
C-type lectins
|
Modulate platelet activity, prevent clotting
|
Antiangiogenesis
|
Viperidae
|
|
|
Phospholipases A2 (PLA2s)
|
Direct toxic action and damage to cell membranes, apoptosis induction
|
Myotoxicity, Myonecrosis
|
Colubridae, Elapidae, Viperidae
|
|
Antibacterial agent
|
L-amino acid oxidase (LAAO)
|
|
|
|
|
|
Phospholipase A2 (PLA2)
|
|
|
|
|
|
Cathelicidin
|
|
|
|
|
Antitumoral
|
|
|
|
|
|
Antiviral agent
|
|
|
|
|
|
Other toxins
|
Lectins
|
|
|
|
|
|
Nerve growth factors
|
Believed to cause cell apoptosis
|
|
Elapidae, Viperidae
|
|
|
Phospholipase inhibitors
|
|
|
|
|
|
Proteinase inhibitors
|
|
|
|
|
|
Complement inhibitors
|
|
|
|
