The biochip will detect botulinum toxin in five hours instead of four days
An express method for diagnosing botulism has been developed
Copper News based on ScienceNOW materials: This Chip Can Tell If You've Been PoisonedFrench scientists have developed a fundamentally new, much faster and more accurate method of diagnosing botulism than the existing one.
A chip with a protein applied to it, with which botulinum toxin interacts, allows you to detect the presence of even very low concentrations of poison in the blood for not four days, as now, but five hours. The method is described in a publication in the journal Biosensors and Bioelectronics (Leveque et al., Direct biosensor detection of botulinum neurotoxin endopeptidase activity in sera from patients with type A botulism).
Botulinum toxin, a protein neurotoxin produced by the spore–forming bacteria Clostridium botulinum, is one of the strongest poisons known to science. Getting into the body, most often when using home-canned products, where bacteria have multiplied under anaerobic conditions, botulinum toxin causes severe damage to the nervous system, progressive paralysis, acute respiratory failure and death. The mortality rate in case of untimely initiation of treatment is 60 percent. In the event that the diagnosis is made on time and adequate therapy is started, the probability of death falls below 5 percent.
Currently, the standard method for diagnosing botulism is a four-day test on laboratory mice, when the presence of a toxin in the patient's blood serum is detected by injecting it into the animal body. If rodents develop symptoms of the disease and they die, the test is considered positive. However, this method, in addition to the excessive and often fatal duration for the patient, is often inaccurate with a relatively low concentration of poison in the blood.
A group of specialists led by molecular neuroscientist Christian Leveque from the Biomedical Research Agency at the INSERM Institute (Marseille, France) attempted to overcome these shortcomings by focusing on the molecular processes underlying the neurotoxic effect of botulinum toxin. At the same time, they chose the most common type of poison, botulinum toxin A. as an object.
In their work, Levesque and his colleagues proceeded from the idea that the damaging effect of botulinum toxin A on the nervous system, which results in paralysis, is due to its cleavage of the SNAP-25 protein, which plays a key role in the transmission of nerve impulses to muscles. The researchers applied SNAP-25 to a thin, two-centimeter-wide chip and exposed it to blood contaminated with botulinum toxin A. To detect the presence of poison, the authors developed a bioengineered monoclonal antibody that reacts specifically with the products of SNAP-25 cleavage with botulinum toxin A. The presence of such a reaction means that the toxin is present in the blood. With the help of such testing, which takes a total of about five hours, the authors were able to detect infection with absolute accuracy (in 11 cases out of 11) even at very low concentrations of botulinum toxin A in the blood, without a single false positive result in the control group, which included healthy people and patients with damage to the nervous system of a different nature.
Leveque's group is currently engaged in conducting more extensive laboratory tests of the method, designed to confirm its effectiveness before introducing it into clinical practice. In addition, the researchers intend to try to apply a similar method to identify other types of botulinum toxin.
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