Venom and Antivenom of the Redback Spider (Latrodectus hasseltii) in Japan. Part I. Venom Extraction, Preparation, and Laboratory Testing.

The redback spider (Latrodectus hasseltii Thorell) reportedly invaded Japan in September 1995. To date, 84 redback spider bite cases have been reported; 7 of these cases employed the antivenom. Antivenom has been imported from Australia in the past, but because of restrictions on exportation 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, using 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 of individuals and subjected to crude purification to yield 4 lots, of which the majority was α-latrotoxin. Among them, a large amount of single lots 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 an anti-lethal titer of antivenom in mice.

Venom and Antivenom of the Redback Spider (Latrodectus hasseltii) in Japan. Part II. Experimental Production of Equine Antivenom against the Redback Spider.

This is the first report on large-scale experimental production of an equine antivenom against the redback spider (Latrodectus hasseltii) lived in Japan. We captured 10,000 redback spiders in Japan and prepared the toxoids of crude venom extract, mixed the toxoids with a mineral oil adjuvant, and immunized healthy horses repeatedly over a period of several weeks. Thereafter, we separated the horse plasma, purified the γ-globulin fraction, and stocked it as a purified antivenom concentrate. Consequently, we manufactured approximately 6,500 vials of a single-dose freeze-dried test lot from a portion of the purified γ-globulin fraction, equivalent to the extract derived from 520 spiders. This test lot had an antitoxin titer comparable to that of a similar drug commercially available overseas (a liquid preparation), and the other quality met all quality reference specifications based on the Minimum Requirements for Biological Products and other guidelines relevant to existing antivenom drug products in Japan.

Retrospective survey to evaluate the safety and efficacy of Japanese botulinum antitoxin therapy in Japan.

Japanese botulinum antitoxins have been used for more than 50 years; however, their safety and therapeutic efficacy are not clear. In order to analyze the available data on botulinum antitoxin therapy in Japan, we surveyed published reports about botulism cases in which botulinum antitoxins were used, and retrospectively analyzed the safety and efficacy of the therapy. A total of 134 patients administered botulinum antitoxins were identified from published reports. Two cases of side effects (1.5%) were detected after antitoxin administration, both not fatal. The fatality rate was 9.4%, and more than 70% of the patients showed improvement in their symptoms and better clinical conditions than those not treated with antitoxins. These data suggest that the therapy with Japanese antitoxins is safe and highly effective.