Antivenom to the venom of the male Sydney funnel-web spider Atrax robustus: preliminary report.

A purified rabbit IgG (antivenom) has been isolated from rabbits immunized with male Atrax robustus venom. This preparation has been shown to neutralize in vitro, male venom in a ratio of 97 microgram of IgG to 1 microgram of male venom. The venoms of a number of other members of the Atrax genus are also neutralized in vitro by this antivenom. Of particular importance is the fact that the venom of the extremely dangerous female A. formidabilis is neutralized. A serum harvest of 55 mL from an immunized rabbit yielded a total of 1.1869 g of immune IgG using the Protein A-Sepharose procedure. This quantity is sufficient antivenom to neutralize in vitro the average yield of 67 spiders. These findings suggest the preparation of an antivenom for human use is now feasible. The antivenom was shown to effectively neutralize venom in monkeys either when it was premixed with the venom before injection or when it was injected separately 10 minutes after injection of venom. This is the first time in-vitro and in-vivo neutralization of this venom has been demonstrated in the monkey. In other studies, a range of non-immunized animal sera was shown to have no inherent ability to neutralize male A. robustus venom in vitro.