Two New Rapid Tests Detect Ricin

New tests for ricin have been developed independently by two groups of scientists. These tests could help safeguard people against potential acts of terrorism involving ricin and also have medical implications.

Ricin, a ribosomal inactivating protein found in castor beans, is one of the agents most likely to be used in acts of aerosol or food-related bioterrorism. It can be obtained easily, and quickly causes death when inhaled or eaten in small amounts. There is no known antidote. Quantitation of ricin also has medical applications, because ricin immunoconjugates have been used as anticancer agents. Current tests capable of identifying ricin by protein recognition methods exist but are generally slow, cumbersome, and inaccurate.

Vern Schramm and Matthew Sturm at the department of biochemistry, Albert Einstein College of Medicine of Yeshiva University (Bronx, NY, USA) developed a new test that detects the presence of active ricin in any sample by measuring the release of adenine from specific ricin substrates. Ricin-catalyzed adenine release from ribosomes stops protein synthesis and is the mechanism of action of this deadly toxin. By coupling adenine release to light formation by firefly luciferase, scientists can visualize the presence of ricin by the simple detection of light. The test can detect nanogram (one-billionth of a gram) amounts of ricin in minutes. A report of this test appeared online in the March 20, 2009 edition of Analytical Chemistry.

A highly selective three-part test was developed by John Barr and Suzanne Kalb from the U.S. Centers for Disease Control and Prevention (CDC; Atlanta, GA, USA). The test involves capturing the ricin protein using special antibodies, evaluating the enzymatic activity of the ricin protein by mass spectrometry, and identifying the ricin protein by its amino acid sequence through mass spectrometry. In laboratory tests using small amounts of ricin spiked into food and body fluids, including milk, apple juice, serum, and saliva, the scientists found that the test was highly specific and accurate in comparison to current tests. This study appeared online in the February 19, 2009 publication of Analytical Chemistry.

Related Links:
Albert Einstein College of Medicine of Yeshiva University
United States Centers for Disease Control and Prevention