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

The research focuses on the extraction and the testing of venom from the redback spider (Latrodectus hasseltii) in Japan. The long-term goal is to manufacture antivenom to treat bites from the spider, which is an invasive species in the country.

Background

• The redback spider (Latrodectus hasseltii Thorell) is an invasive species in Japan, first reported in 1995.
• There have been 84 bite incidents reported, with seven cases rectified using antivenom imported from Australia.
• The supply of the antivenom faced limitations due to export restrictions, thus, nearly all available antivenom in Japan is estimated to expire by 2014. In order to maintain supply, a plan was proposed in 2014 to locally produce and store horse antiserum from redback spiders native to Japan.

Venom Extraction and Preparation

• A total of 11,403 female redback spiders were caught alive for the study, predominantly from Hyogo and Osaka prefecture.
• Out of these, venom was successfully extracted and crudely purified from 10,007 spiders.
• The primary component of the resulting four venom lots was identified as α-latrotoxin, a potent neurotoxin.
• One of the venom lots contained a large amount of pure toxin, roughly estimated at 236 mg of protein, intended for creating the antivenom by immunizing horses.

Toxicity Testing and Antivenom Development

• Researchers determined the lethal toxicity of the venom with an LD50 (a standard measure of acute toxicity) of 9.17 μg per mouse.
• The antivenom’s effectiveness against the venom’s lethal effects was quantified, guiding further development and refinement of the antivenom.

Implications of the Research

• The study presents crucial initial steps towards locally producing antivenom in Japan, which could offer an effective way to treat unfortunate encounters with the redback spider.
• The collected data on venom toxicity would also contribute to understanding the potential impacts and risks of the invasive spider species, thereby informing public health and pest management strategies.