Anthrax detector

Researchers in Switzerland have developed a detector for deadly anthrax spores based on a monoclonal antibody that recognises a specific sugar on the bacterium.¹ This new test promises to be just as accurate but far simpler to do than current detection methods. 

Spores of the dreaded Bacillus anthracis have already been used as a bioweapon against civilians. Once inhaled, the anthrax pathogen almost always leads to death if the victims are not treated within 24-48 hours. There are several diagnostic tests for anthrax but they are time-consuming. According to Peter Seeberger of the Swiss Federal Institute of Technology (ETH) in Zürich, and colleagues at the Swiss Tropical Institute, and the University of Bern, also in Switzerland, in the event of a bioweapon attack, a fast and reliable test is essential if lives are to be saved.  

Seeberger and his team's novel approach to anthrax detection is based on immunology. Diagnostic tests based on immunology are usually simple and quick. However, the surface features of anthrax spores are similar to other common bacteria so early immunological tests for anthrax fail to distinguish between these and deadly anthrax. Fortunately, the Swiss scientists discovered a carbohydrate consisting of four sugar components on the surface of anthrax spores. Three of these sugar molecules are found in other bacteria, but the fourth, anthrose, is unique to anthrax. Seeberger's team focused on this molecule as the flag they needed to diagnose anthrax. 

To make a fast immunological test for any disease, scientists have to make special proteins known as antibodies, which detect and latch on to the target molecule. Seeberger and his team synthesised anthrose in the laboratory and then attached this sugar to a 'carrier' protein. This innocuous sugar-protein complex was then injected into mice. The mouse immune system quickly spots the invading molecule and recognises it as alien, triggering the production of antibodies. These antibodies are specific to the sugar molecule anthrose. By using monoclonal antibody technology the researchers can mass produce these antibodies in the laboratory to incorporate into their test kit. 

From their tests to see if the antibodies can identify anthrax, the researchers found that they bind specifically to anthrax spores and to no other bacteria closely related to B. anthracis. 'Our results demonstrate that small differences in the carbohydrates on cell surfaces can be used to obtain specific immune reagents', says Seeberger. 'Our new antibodies will be used as the basis for highly sensitive anthrax diagnosis and will contribute to the development of new therapeutic approaches'.