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

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 gamma-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 gamma-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.