Venom and antivenom of redback spider (Latrodectus hasseltii) in Japan.

I. Venom extraction, preparation, and laboratory testing.

Abstract

In September 1995 it was reported that the redback spider (Latrodectus hasseltii Thorell) had invaded Japan. To date 84 redback spider bite cases have been reported, and of these, seven employed the antivenom. In the past, antivenom have been imported from Australia, but because of restrictions on exportation thereof it was evident that nearly all of the antivenom present in Japan would expire during 2014. In 2014 a plan was proposed to experimentally manufacture and stockpile a horse antiserum for ourselves, employing redback spiders indigenous to Japan. A total of 11,403 female spiders were captured alive: 1,217 from the vicinity of Nishinomiya City, Hyogo prefecture, and 10,186 from Osaka prefecture. Of these, 10,007 females were dissected and the venom was extracted from the venom glands removed from each individual and subjected to crude purification to give 4 lots, of which the majority was α-latrotoxin. Among them, a large amount of single lot with an estimated protein content of 236 mg is subsequently scheduled to be used for immunizing horses. We also determined lethal toxicity of the venom (LD₅₀: 9.17 μg per mouse), and established the assay for the determination of anti-lethal titer of antivenom in mouse.