Magnetic Test Developed For Cholera Toxin

A test has been developed than can detect the toxin of the bacterium Vibrio cholerae, the causative agent of cholera.

A molecular mimicry strategy can used to identify targeting ligands that bind to the cholera toxin B subunit (CTB) that can be found in blood, water or other fluids.

Scientists at the University of Central Florida, (Orlando, FL, USA), used specially prepared nanoparticles of iron oxide, coated with a type of sugar called dextran. They looked for specific characteristics of the cholera toxin receptor (GM1) found on cells' surface in the patient's gut, and then they introduced these features to their nanoparticles.

When the magnetic nanoparticles are added to water, blood, or other fluids to be tested, the cholera toxin binds to the nanoparticles in a way that can be easily detected by instruments. The scientists say the test hardware can be turned into portable gear that health care workers could use in the field. The approach also shows promise for treating cholera intoxication.

The use of magnetic relaxation switches is an emerging technology that has been utilized for the sensitive and fast detection of clinically relevant biomolecules, cells, and metabolic activity in complex media. In the present study, the investigators used molecular mimicry to identify by magnetic relaxation and confirm by surface plasmon resonance (SPR) that galactose and dextran interact with CTB. This information has been used to develop selective magnetic relaxation nanoswitches to detect the cholera toxin. Vibrio cholerae produces the toxin that can cause severe diarrhea, which can lead to rapid dehydration and death. Prompt treatment thus is essential, and yet existing tests to diagnose cholera are time-consuming, expensive, and require the use of complex equipment.

Cholera affects more than 200,000 people annually, mainly in developing countries, and causes about 5,000 deaths mainly amongst the infants, children, and the elderly.

Cholera is rampant in Haiti and almost 40 other countries and the development of a fast, simple test to detect the toxin that causes the disease is paramount. The study was published on January 12, 2011, in Bioconjugate Chemistry.

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