Neurotoxic effects of venoms from seven species of australasian black snakes (Pseudechis): Efficacy of black and tiger snake antivenoms

Abstract

1. Pseudechis species (black snakes) are among the most widespread venomous snakes in Australia. Despite this, very little is known about the potency of their venoms or the efficacy of the antivenoms used to treat systemic envenomation by these snakes. The present study investigated the in vitro neurotoxicity of venoms from seven Australasian Pseudechis species and determined the efficacy of black and tiger snake antivenoms against this activity. 2. All venoms (10 microg/mL) significantly inhibited indirect twitches of the chick biventer cervicis nerve-muscle preparation and responses to exogenous acetylcholine (ACh; 1 mmol/L), but not to KCl (40 mmol/L), indicating activity at post-synaptic nicotinic receptors on the skeletal muscle. 3. Prior administration of either black or tiger snake antivenom (5 U/mL) prevented the inhibitory effects of all Pseudechis venoms. 4. Black snake antivenom (5 U/mL) added at t90 (i.e. the time-point at which the original twitch height was reduced by 90%) significantly reversed the effects of P. butleri (28+/-5%), P. guttatus (25+/-8%) and P. porphyriacus (28+/-10%) venoms. Tiger snake antivenom (5 U/mL) added at the t90 time-point significantly reversed the neurotoxic effects of P. guttatus (51+/-4%), P. papuanus (47+/-5%) and P. porphyriacus (20+/-7%) venoms. 5. We show, for the first time, the presence of neurotoxins in the venom of these related snake species and that this activity is differentially affected by either black snake or tiger snake antivenoms.