TINY but deadly. Of the 7000 people bitten every year in Brazil by brown recluse spiders, also known as reapers, 1.5 per cent die. There is an antivenom, but it can trigger side effects, and animals suffer so we can produce it. Now a Brazilian team has developed a synthetic version of the venom, allowing them to make a safer, kinder antidote.
Normally, antivenom is made by injecting horses with spider venom to stimulate the production of antibodies. These are then extracted as a serum and given to bite victims.
To make an alternative, Carlos Chávez-Olórtegui of the Federal University of Minas Gerais and colleagues inserted genes into Escherichia coli. These genes code for surface features on the toxin that trigger antibody production. The bacteria then churned out a non-toxic, venom-like substance. When this was given to rabbits, the antibodies they made protected other rabbits against the spider venom almost as well as antibodies from horses exposed to the real thing (Vaccine, doi.org/mg3).
The synthetic venom is free from impurities so any serum made from it should cause fewer side effects.
This article appeared in print under the headline “Don’t fear the reaper spider”