Scientists could replace mice with liposomes to test botulinum

Researchers from ETH Zurich in Switzerland recently filed a patent application for a method to test the biological activity of the botulinum neurotoxin using lipid vesicles to replace mice in experiments.

The BoNT, which is produced by the Clostridium botulinum bacterium, is an extremely strong poison that can be found in insufficiently sterilized canned vegetables, meats and sausages. The poison can cause paralysis and apnea, but it is also used to treat chronic conditions and in the cosmetics industry, reports.

Because BoNT is produced by bacteria, regulatory authorities require that the toxicity of every batch of therapeutic agent containing BoNT be tested with the mouse LD50 test. These routine tests in the pharmaceutical industry of the U.S. and the E.U. kill more than half a million mice per year.

Oliver Weingart, an ETH-Zurich researcher, and collaborators with the Spiez Laboratory developed a system to test BoNT without laboratory animals or living cells. The system measures the toxic activity of the neurotoxin using artificially produced lipid membrane vesicles called liposomes.

The system contains reaction compartments that mimic nerve-cell receptors to which the neurotoxin can bind. When the toxin becomes active, the system is set up to emit a measurable fluorescence to detect the BoNT concentration.

"The liposomes are easy and inexpensive to produce, and no special training is needed for handling by laboratory staff," Weingart said, according to "The system is very sensitive."

The aim of the system is to be even more sensitive than the detection limit in mice studies, which is approximately ten picograms of BoNT. The system may also be faster, with a final result available in less than 24 hours versus the mice study, which can take up to four days, reports.

According to the Center for Biosecurity of UPMC in Baltimore, botulinum toxins are considered biological weapons because they are extremely lethal and potent, some of the toxins are relatively easy to produce and transport and people with botulism require prolonged intensive hospital care.