Comparative Studies of the Venom of a New Taipan Species, Oxyuranus temporalis, with Other Members of Its Genus

Abstract

Taipans are highly venomous Australo-Papuan elapids. A new species of taipan, the Western Desert Taipan (Oxyuranus temporalis), has been discovered with two specimens housed in captivity at the Adelaide Zoo. This study is the first investigation of O. temporalis venom and seeks to characterise and compare the neurotoxicity, lethality and biochemical properties of O. temporalis venom with other taipan venoms. Analysis of O. temporalis venom using size-exclusion and reverse-phase HPLC indicated a markedly simplified “profile” compared to other taipan venoms. SDS-PAGE and agarose gel electrophoresis analysis also indicated a relatively simple composition. Murine LD50 studies showed that O. temporalis venom is less lethal than O. microlepidotus venom. Venoms were tested in vitro, using the chick biventer cervicis nerve-muscle preparation. Based on t90 values, O. temporalis venom is highly neurotoxic abolishing indirect twitches far more rapidly than other taipan venoms. O. temporalis venom also abolished responses to exogenous acetylcholine and carbachol, indicating the presence of postsynaptic neurotoxins. Prior administration of CSL Taipan antivenom (CSL Limited) neutralised the inhibitory effects of all taipan venoms. The results of this study suggest that the venom of the O. temporalis is highly neurotoxic in vitro and may contain procoagulant toxins, making this snake potentially dangerous to humans.

Venoms of related mammal-eating species of taipans (Oxyuranus) and brown snakes (Pseudonaja) differ in composition of toxins involved in mammal poisoning

“…2). This finding confirms that the very rapid neurotoxic activity of O. temporalis venom in chick biventer cervicis physiological assay, reported by Barber et al [39], is due to an extremely high concentration of postsynaptic α-neurotoxins (iBAQ abundance = 97.9%). A recent study sequenced the α-Elapitoxin-Ot1a short-chain αneurotoxin from this species and found it to be a potent and abundant venom constituent [40].…”

“…chains belonging to taipoxin and paradoxin clades ( There is an indication that α-neurotoxin abundance may vary geographically. For example, a more reduced effect of Saibai Island Oxyuranus scutellatus venom on chick biventer cervicis contractile response to acetylcholine suggests that this population would have even lower expression of α-neurotoxins than the specimens from the mainland [39]. O. scutellatus and O. microlepidotus venoms also contained prothrombinase toxins, but less than in some Pseudonaja venoms (Table 1).…”

Isolation and Pharmacological Characterization of α-Elapitoxin-Ot1a, a Short-Chain Postsynaptic Neurotoxin from the Venom of the Western Desert Taipan, Oxyuranus temporalis

“…The toxic components often include neurotoxins which assist in the immobilization and capture of prey but also may cause clinical neurotoxicity following systemic envenoming in humans. We have recently studied O. temporalis venom and shown that the reverse-phase HPLC venom profile consists of only a few peaks with the major peak eluting around 15 min [ 4 ]. Previous studies conducted in our laboratory have shown that, under the same reverse-phase HPLC conditions, short-chain postsynaptic neurotoxins elute from the reverse phase column between 15–17 min [ 16 , 17 , 21 , 22 ].…”

“…O. temporalis venom was obtained as previously described [ 4 ] from two live specimens of O. temporalis held at the Adelaide Zoo (Adelaide, South Australia, Australia). After extraction, the venom was frozen with dry ice, transferred into a −20 °C freezer and then lyophilized.…”

“…Due to the remote location of O. temporalis , only a handful of specimens have been caught and, as such, limited information exists about this species [ 1 , 2 , 3 ]. We recently showed that O. temporalis venom displays marked post-synaptic neurotoxic activity in isolated skeletal muscle [ 4 ].…”