Oxyuranus Scutellatus Canni Research Articles

Habitat-modification by an herbivorous marsupial benefits the Papuan Taipan, Oxyuranus scutellatus canni Slater 1956, within an anthropogenic environment in Central Province, Papua New Guinea

Habitat-modification by an herbivorous marsupial benefits the Papuan Taipan, Oxyuranus scutellatus canni Slater 1956, within an anthropogenic environment in Central Province, Papua New Guinea

Antivenom production in the alpaca (Vicugna pacos): Monovalent and polyvalent antivenom neutralisation of lethal and procoagulant toxins in Australian elapid venoms

Alpaca (Vicugna pacos), like all other members of the camelid family, produce a unique heavy chain only IgG subclass. This form of IgG has been proposed as having superior neutralising properties and improved safety as compared with conventional mammalian IgG-based immunotherapeutics. The objective of this study was to investigate the potential of alpaca antibodies to neutralise the lethal and procoagulant properties of several Australian elapid snake venoms. Various experimental antivenoms were produced by immunisation of alpaca (Vicugna pacos) with combinations of five Australian elapid snake venoms: tiger snake (Notechis scutatus), eastern brown snake (Pseudonaja textilis), Papuan taipan (Oxyuranus scutellatus canni), mulga snake (Pseudechis australis) and common death adder (Acanthophis antarcticus). Venoms were emulsified in Freund’s Incomplete Adjuvant and alpaca repeatedly immunised. Having previously shown that such alpaca produce persistent venom-specific antibody responses with minimal physiological impact on the animal, the current report demonstrates that polyvalent alpaca antivenom neutralises the lethal effects of three elapid venoms (tiger, brown and Papuan taipan venoms). Such lethality neutralisation was, however, of generally lower potency, but of the same order of magnitude, when compared with bioCSL monovalent antivenoms (brown, tiger and taipan antivenoms). By contrast, the monovalent alpaca tiger and brown snake antivenom were found to be superior to the equivalent bioCSL monovalent antivenoms when considering the neutralisation of the procoagulant effects of the respective immunising venoms. The bioCSL polyvalent antivenom also less potent, when compared with the alpaca taipan monovalent antivenom, against Papuan taipan venom procoagulant neutralisation. These findings support the potential of camelid immunoglobulin for the development of novel elapid specific antivenoms.

Antivenom production in the alpaca (Vicugna pacos): physiological and antibody responses to monovalent and polyvalent immunisation with Australian elapid venoms

Alpaca (Vicugna pacos) are domesticated members of the camelid family that have been shown to produce an IgG subclass that is heavy chain only IgG. This camelid-type IgG has been postulated to have improved neutralising properties and reduced immunogenicity, compared with conventional mammalian IgG. This study was undertaken to describe the physiological and antibody responses of alpaca (Vicugna pacos) used for the production of an experimental camelid antivenom. Various antivenom products were developed by immunisation of alpaca with combinations of five Australian elapid snake venoms: common tiger snake (Notechis scutatus), eastern brown snake (Pseudonaja textilis), Papuan taipan (Oxyuranus scutellatus canni), mulga snake (Pseudechis australis) and common death adder (Acanthophis antarcticus) were emulsified with Freund’s Adjuvant and injected monthly using a low dose multi-site approach. Venom specific immune responses were monitored by ELISA. Physiological effects upon alpaca were monitored by clinical examination combined with serial haematology and biochemical profiles. Serum was harvested once immune responses had peaked and the IgG fraction concentrated by ammonium sulphate precipitate of non-IgG proteins. Total serum IgG and total serum protein concentrations increased and decreased in synchrony with boosting specific antibodies. The difference in serum creatinine kinase concentration measured at 24h after each of the first three immunisations decreased as the alpaca mounted an antibody response to the venom antigens measured by ELISA. In conclusion, alpaca responded to repeated immunisation with various Australian elapid venoms by mounting an increasing antibody response that persisted following prolonged rest with minimal physiological impact on the animal.

Variations in the pharmacological profile of post-synaptic neurotoxins isolated from the venoms of the Papuan ( Oxyuranus scutellatus canni) and coastal ( Oxyuranus scutellatus scutellatus) taipans

Based on murine LD 50 values, the taipans (i.e. Oxyuranus microlepidotus, Oxyuranus scutellatus and Oxyuranus scutellatus canni) are the most venomous snake genus in the world. Despite this, little is known about the toxins contained in their venoms. The aim of the present study was to isolate and characterise post-synaptic neurotoxins from the venoms of the Papuan taipan ( O. s. canni) and coastal taipan ( O. scutellatus), and to compare their pharmacology. A 6770 Da toxin (i.e. α-oxytoxin 1) and a 6781 Da toxin (i.e. α-scutoxin 1) were isolated from the venoms of O. s. canni and O. scutellatus, respectively, using reverse-phase high performance liquid chromatography. Both α-oxytoxin 1 (0.3–1 μM) and α-scutoxin 1 (0.1–1 μM) caused concentration-dependent inhibition of indirect twitches in the chick biventer cervicis nerve-muscle preparation. Contractile responses to exogenous carbachol (CCh), but not potassium chloride (KCl), were inhibited by both toxins, suggesting a post-synaptic mode of action. The inhibitory effect of α-oxytoxin 1 was reversed by washing. Cumulative concentration–response curves to CCh were obtained in the presence and absence of the toxins with the subsequently determined pA 2 of α-scutoxin 1 being 44.7-fold higher than α-oxytoxin 1 (i.e. 8.38 ± 0.59 versus 7.62 ± 0.04). The current study shows that Papuan taipan and coastal taipan venom both contain potent post-synaptic neurotoxins which exhibit different pharmacological profiles. The effect of α-oxytoxin 1 is atypical of most snake venom post-synaptic neurotoxins displaying a ‘competitive’ mode of action, whereas α-scutoxin 1 possesses pseudo-irreversible or non-competitive activity.

Isolation and Pharmacological Characterization of Cannitoxin, a Presynaptic Neurotoxin from the Venom of the Papuan Taipan (Oxyuranus scutellatus canni)

The Papuan taipan (Oxyuranus scutellatus canni) is widely distributed throughout much of Papua New Guinea. Although neurotoxicity is a major symptom of envenomation, no neurotoxins have been isolated from this venom. Using a series of size exclusion chromatography steps, we report the isolation of cannitoxin, a presynaptic neurotoxin (44,848 Da) that represents approximately 16% of the whole venom. The toxin displayed high phospholipase A2 (PLA2 activity (330 +/- 5 micromol/min/mg) and caused concentration-dependent (11-66 nM) inhibition of indirect (0.2 ms; 0.1 Hz; supramaximal V) twitches of the chick biventer cervicis nerve-muscle preparation without effecting nicotinic receptor agonists. Prior addition of CSL Taipan antivenom (5 U/ml) or inhibition of phospholipase A2 activity by incubation with 4-bromophenacyl bromide prevented the inhibition of twitches. Cannitoxin is composed of three different subunits, alpha, beta, and gamma, with the possibility of two beta isomers. However, only the alpha subunit displayed in vitro neurotoxic activity of its own. Thus, cannitoxin is similar in structure and pharmacology to taipoxin, which has been isolated from the closely related Australian species O. scutellatus scutellatus (coastal taipan).

A pharmacological examination of venom from the Papuan taipan: ( Oxyuranus scutellatus canni)

The Papuan taipan ( Oxyuranus scutellatus canni) is the third most venomous terrestrial snake in the world, however, little is know about the pharmacology of the venom. In the chick biventer cervicis muscle, venom (10 μg/ml) abolished nerve-mediated twitches (time to 90% inhibition ( t 90) 44±5 min, n=9). This inhibition was unaffected by prior incubation of the venom with the phospholipase A inhibitor 4-bromophenacyl bromide (4-BPB; 0.72 mM) ( t 90 48±7 min, n=8). The mouse phrenic nerve diaphragm preparation displayed greater sensitivity to venom (10 μg/ml) ( t 90 25±1 min, n=6). In the chick biventer muscle, venom (10 μg/ml) significantly inhibited responses to acetylcholine (1 mM) and carbachol (20 μM), but not KCl (40 mM), indicating activity at post-synaptic nicotinic receptors. Venom (10 μg/ml) did not affect direct muscle stimulation. Venom (3–30 μg/ml) produced dose-dependant contractions of the guinea-pig ileum. Contractile responses were significantly inhibited by indomethacin (1 μM) or prior incubation of the venom with 4-BPB (0.72 mM) indicating involvement of a PLA component. In rat phenylephrine (0.3 μM) precontracted aortae, venom (3–100 μg/ml) produced endothelium-independent relaxation which was unaffected by prior incubation of venom (30 μg/ml) with 4-BPB (0.72 mM). In anaesthetised rats, 10 μg/kg (i.v.) venom produced rapid respiratory and cardiovascular collapse while 5 μg/kg (i.v.) venom produced only a small transient decrease in mean arterial blood pressure. Prior administration of 5 μg/kg (i.v.) venom enabled subsequent administration of 10 and 100 μg/kg (i.v.) venom without respiratory or cardiovascular collapse. Further work is required to identify specific toxins with the above pharmacological activity.

P18 Haemostatic changes induced in 84 humans bitten by the Papuan taipan (Oxyuranus scutellatus canni) and recovery following antivenom

Haemophilia and Haemostasis Centre, Department of Haematology, Royal Free Hospital and School of Medicine, London, UK

Electrocardiographic abnormalities in patients bitten by taipans ( Oxyuranus scutellatus canni) and other elapid snakes in Papua New Guinea

Envenoming by a number of species of snake may affect the myocardium or cause electrocardiographic changes; several different mechanisms have been proposed. In a prospective study of snake bite in Papua New Guinea, electrocardiographic changes were observed in 36 of 69 patients (52%) envenomed by the taipan ( Oxyuranus scutellatus), 2 of 6 (33%) envenomed by death adders ( Acanthophis sp.) and one envenomed by the brown snake ( Pseudonaja textilis). Septal T wave inversion and bradycardias, including atrioventricular block, were the commonest abnormalities. There was no haemodynamic deterioration. The cause of these changes is uncertain; only 2 of 24 patients (8·3%) with electrocardiographic changes had markedly elevated plasma concentrations of cardiac troponin T, a sensitive and specific marker of myocardial damage. This suggests that myocardial damage is uncommon following bites by these species. Electrocardiographic abnormalities are most likely to have been caused by a direct toxic effect of a venom component upon cardiac myocyte function; in taipan bites, taicatoxin, a calcium channel blocker, might be responsible.

Failure of 3,4-diaminopyridine and edrophonium to produce significant clinical benefit in neurotoxicity following the bite of Papuan taipan ( Oxyuranus scutellatus canni)

Progressive systemic neurotoxicity is a common feature in patients envenomed following the bite of a Papuan taipan ( Oxyuranus scutellatus canni). Respiratory paralysis, which commonly results, accounts for considerable morbidity and mortality. Established neurotoxicity does not respond to antivenom. In this study, a combination of clinical and electrophysiological variables was used to assess the effect of edrophonium and 3,4-diaminopyridine in patients with significant neurotoxicity. Both drugs produced minor electrophysiological and clinical changes in envenomed patients. This effect was maximal when the 2 drugs were used in combination, but was insufficient to be of significant clinical benefit. Neither drug can be recommended for use in the management of Papuan taipan bite.

Electrophysiological findings in patients envenomed following the bite of a Papuan taipan ( Oxyuranus scutellatus canni)

Electrophysiological studies were done on patients with systemic neurotoxicity following the bite of a Papuan taipan ( Oxyuranus scutellatus canni). Evoked compound muscle action potentials decreased and increased in tandem with clinical deterioration and recovery. Nerve conduction velocities did not change in envenomed patients and were consistent with control studies. Repetitive nerve stimulation studies showed decrementai responses in envenomed patients with post-tetanic potentiation followed by post-tetanic exhaustion. The findings are consistent with studies in vitro which suggested that the major action of neurotoxins in Australian taipan venom is at the synapse. The observation that electrophysiological data correlate closely with the clinical condition of the patient has potential application in the assessment of interventions in the management of snake bite victims.

Snake bites by the Papuan taipan (Oxyuranus scutellatus canni): paralysis, hemostatic and electrocardiographic abnormalities, and effects of antivenom.

One hundred sixty-six patients with enzyme immunoassay-proven bites by taipans (Oxyuranus scutellatus canni) were studied in Port Moresby, Papua New Guinea. One hundred thirty-nine (84%) showed clinical evidence of envenoming: local signs were trivial, but most developed hemostatic disorders and neurotoxicity. The blood of 77% of the patients was incoagulable and 35% bled spontaneously, usually from the gums. Fifty-one per cent had microscopic hematuria. Neurotoxic signs (ptosis, ophthalmoplegia, bulbar paralysis, and peripheral muscular weakness) developed in 85%. Endotracheal intubation was required in 42% and mechanical ventilation in 37%. Electrocardiographic abnormalities (sinus bradycardia and septal T wave inversion) were found in 52% of a group of 69 unselected patients. Specific antivenom raised against Australian taipan venom was effective in stopping spontaneous systemic bleeding and restoring blood coagulability but, in most cases, it neither reversed nor prevented the evolution of paralysis even when given within a few hours of the bite. However, early antivenom treatment was associated statistically with decreased incidence and severity of neurotoxic signs. The low case fatality rate of 4.3% is attributable mainly to the use of mechanical ventilation, a technique rarely available in Papua New Guinea. Earlier use of increased doses of antivenoms of improved specificity might prove more effective.

The efficacy of antivenom in the treatment of bites by the Papuan taipan ( Oxyuranus scutellatus canni)

A prospective series of 156 patients systemically envenomed following the bite of a Papuan taipan ( Oxyuranus scutellatus canni) were studied. All patients were treated with appropriate antivenom and clinical course and outcome were compared. The proportion of patients requiring intubation was significantly smaller, and the time to resolution of neurotoxicity and discharge from hospital significantly shorter, in patients receiving antivenom no more than 4 h after the bite. No significant difference in outcome was demonstrated between patients receiving antivenom at various times after 4 h. No difference was demonstrated in the times to restoration of coagulability between the 2 groups. The only significant difference between a small number of patients given 2 vials of antivenom and patients given a single vial at the same time after envenoming was a marginally shorter duration of intubation in those who required it. The study suggests that, to achieve significant clinical benefit in Papuan taipan bite, antivenom must be given as early as possible.

Coagulopathy following bites by the Papuan taipan (Oxyuranus scutellatus canni).

The mechanisms of haemostatic failure were studied in 87 patients bitten by the Papuan taipan (Oxyuranus scutellatus canni). Eighty (92%) had evidence of a coagulopathy on laboratory testing; 36 (41.4%) developed spontaneous systemic bleeding, although this was rarely of clinical significance. Coagulation assays in 48 completely defibrinated patients showed marked reductions in factors V and VIII and reductions in factors II, IX, XI, XII and XIIIA. There was a reduction in plasminogen and alpha 2-antiplasmin levels and both total and cross-linked fibrin(ogen) degradation products (FDP) levels were elevated. The mean platelet count was initially decreased and fell further during admission. Similar but less severe changes were seen in patients who were mildly defibrinated. Following treatment with antivenom, fibrinogen levels rose rapidly and coagulability was restored within 6-12 h in 93% of patients. These abnormalities may be primarily attributable to the prothrombin activator present in taipan venom, but it is likely that other uncharacterized venom components contributed.

Neurotoxicity and haemostatic disturbances in patients envenomed by the Papuan black snake ( Pseudechis papuanus)

Among 335 patients presenting with snakebites in Central Province, Papua New Guinea, nine were proved by enzyme immunoassay to have been bitten by Papuan black snakes ( Pseudechis papuanus). Seven showed clinical evidence of envenoming. Early symptoms included vomiting and tender local lymph nodes. Five patients had neurotoxic signs and one required mechanical ventilation. Spontaneous systemic bleeding occurred in two patients. Coagulation studies in four patients showed thrombocytopenia, prolongation of prothrombin time, mild defibrination and depletion of other clotting factors with elevated fibrin(ogen) degradation products and other evidence of fibrinolysis. One patient developed mild renal dysfunction. There was no evidence of intravascular haemolysis or rhabdomyolysis. These clinical observations, which do not distinguish victims of P. papuanus from those of taipans ( Oxyuranus scutellatus canni), suggest that the venom contains neurotoxic, haemorrhagic and mild procoagulant activities. Only two other cases of proven envenoming by this species have been reported. There appears to have been a decline in the abundance of this species, and hence its medical importance, over the last 25 years.

The effect of bites by the Papua New Guinean taipan (Oxyuranus scutellatus canni): D. Lalloo, A. Trevett, M. Paul, A. Korinihona, J. Mapao, B. Danga-Christian, I. Laurenson, B. Mayo, A. Sawer, S. Naraqi, D. Theakston and D. Warrell (Department of Clinical Sciences, University of Papua New Guinea; Liverpool School of Tropical Medicine, U.K.; and Centre for Tropical Medicine, University of

The effect of bites by the Papua New Guinean taipan (Oxyuranus scutellatus canni): D. Lalloo, A. Trevett, M. Paul, A. Korinihona, J. Mapao, B. Danga-Christian, I. Laurenson, B. Mayo, A. Sawer, S. Naraqi, D. Theakston and D. Warrell (Department of Clinical Sciences, University of Papua New Guinea; Liverpool School of Tropical Medicine, U.K.; and Centre for Tropical Medicine, University of

Coagulopathy following Papua New Guinean taipan (Oxyuranus scutellatus canni) envenoming: D. Lalloo, J. Black, S. Naraqi, D. Owens, A. Chitolie, R. A. Hutton, R. D. G. Theakston and D. A. Warrell (Centre for Tropical Medicine, University of Oxford, U.K.; University of Papua New Guinea, Boroko; Royal Free Hospital, London, U.K.; Liverpool School of Tropical Medicine, U.K.).

Coagulopathy following Papua New Guinean taipan (Oxyuranus scutellatus canni) envenoming: D. Lalloo, J. Black, S. Naraqi, D. Owens, A. Chitolie, R. A. Hutton, R. D. G. Theakston and D. A. Warrell (Centre for Tropical Medicine, University of Oxford, U.K.; University of Papua New Guinea, Boroko; Royal Free Hospital, London, U.K.; Liverpool School of Tropical Medicine, U.K.).

Envenoming from the papuan taipan (Oxyuranus scutellatus canni): B. Currie, D. Theakston and D. Warrell (Menzies School of Health Research, Darwin NT, Australia, and University of Papua New Guinea).

Envenoming from the papuan taipan (Oxyuranus scutellatus canni): B. Currie, D. Theakston and D. Warrell (Menzies School of Health Research, Darwin NT, Australia, and University of Papua New Guinea).

An epidemiological study of snake bite envenomation in Papua New Guinea

We report a study of 347 patients with snake bite envenomation in Papua New Guinea. The male: female ratio of the victims was 1.6:1 and their mean age was 24.5 years; 26% were children less than 15 years old. In all cases in which the bite site was known (334) the snake had bitten the extremities of the victim, with 71.3% of these bites being on the ankle or below. The patients came from three regions: urban Papua, rural Papua and (mostly rural) New Guinea. Snake bites occurred more frequently during the daytime in all regions, but this pattern was less obvious in New Guinea (P = 0.004), reflecting the predominance of the death adder (Acanthophis antarcticus) in New Guinea and of the taipan (Oxyuranus scutellatus canni) in Papua. Bites were commoner in the rainy season (November to April) in all groups, but this was less noticeable in rural Papua and New Guinea (P = 0.004). This may relate to seasonal activities of the rural population. The female:male ratio for patients from rural areas was higher for those 30 years of age and over than for those under 30 (P = 0.034), probably reflecting the increased gardening workload of older women. The incidence of envenomation and mortality rates after snake bite in Papua appear to have changed little over 25 years. However, increased relative numbers of taipans seem to be occurring in central Papua possibly related to the cane toad (Bufo marinus) and deforestation. We calculate the annual incidence of envenomation and the mortality rate per 100,000 to be 81.8 and 4.3, respectively, for rural central Papua, 21.8 and 2.1 for urban central Papua, and 3.0 and less than 1.0 for the Madang region of New Guinea. The importance of a standard management protocol and of improved first aid are emphasised. Language: en

An epidemiological study of snake bite envenomation in Papua New Guinea

We report a study of 347 patients with snake bite envenomation in Papua New Guinea. The male: female ratio of the victims was 1.6:1 and their mean age was 24.5 years; 26% were children less than 15 years old. In all cases in which the bite site was known (334) the snake had bitten the extremities of the victim, with 71.3% of these bites being on the ankle or below. The patients came from three regions: urban Papua, rural Papua and (mostly rural) New Guinea. Snake bites occurred more frequently during the daytime in all regions, but this pattern was less obvious in New Guinea (P = 0.004), reflecting the predominance of the death adder (Acanthophis antarcticus) in New Guinea and of the taipan (Oxyuranus scutellatus canni) in Papua. Bites were commoner in the rainy season (November to April) in all groups, but this was less noticeable in rural Papua and New Guinea (P = 0.004). This may relate to seasonal activities of the rural population. The female:male ratio for patients from rural areas was higher for those 30 years of age and over than for those under 30 (P = 0.034), probably reflecting the increased gardening workload of older women. The incidence of envenomation and mortality rates after snake bite in Papua appear to have changed little over 25 years. However, increased relative numbers of taipans seem to be occurring in central Papua possibly related to the cane toad (Bufo marinus) and deforestation. We calculate the annual incidence of envenomation and the mortality rate per 100,000 to be 81.8 and 4.3, respectively, for rural central Papua, 21.8 and 2.1 for urban central Papua, and 3.0 and less than 1.0 for the Madang region of New Guinea. The importance of a standard management protocol and of improved first aid are emphasised.

A collection of nematodes from snakes from Papua New Guinea

Kalicephalus amplicervix n.sp. (snake host species not recorded) is distinguished by having the greatest body width immediately posterior to the large head capsule. K. willeyi was identified from Oxyuranus scutellatus canni, K. australiensis and Moaciria chondropythonis from Chondropython viridis, and Abbreviata confusa from Demansia olivacea papuensis. K. willeyi is a new host and geographical record, and K. australiensis a new host record.