Studies on the venom of Oxyuranus microlepidotus

The Australian Small-scaled Snake, Oxyuranus microlepidotus , recently rediscovered, is the world's most venomous snake, with a murine LD50 of 0.01 mg/kg. Recently developed immunological techniques, combined with a whole animal model, have enabled us to measure accurately the mass of venom actually injected by a striking snake. The venom of this species contains at least six identified protein fractions, and one or more of these possesses potent neurotoxic action. An initial assessment of the molecular weights of each of these is reported. This study describes field biting experiments applicable to potential human snake-bite, and presents data concerning the injected venom:LD50 ratio which is an index of potential human lethality. This snake delivers an average mass of 17.3 mg in a strike, and the injected mass:LD50 ratio is 1730, the highest recorded for any snake. Comparative results for five other Elapidae whose venom contains potent neurotoxins are also presented. An average mass of 0.6 mg of venom is split on the skin surface during a strike, and 40% of this can be recovered within three hours after a simulated bite. As with other Elapidae studied to date, an adequate mass of venom remains on the skin for an accurate species diagnosis to be made in the case of human snake-bite.