Monoclonal Antibody based system for Anthrax detection

According to Swiss Radio International report, a Swiss research team has developed a simple and highly sensitive testing system for anthrax detection, which is better than the already existing ones.The report says that the new system can be used to detect anthrax spores that are used in biological warfare.

In October2001, the United States was hit by an anthrax attack that killed 5 people.They died from contaminated letters sent to political and media organizations. This incident invigorated the need of quick and reliable anthrax detection tests.

An immunological test that gives accurate results in minutes has been successfully developed by a team of Swiss researchers. The existing genetic methods are more time consuming and expensive.

"An immunological test takes five to ten minutes to work and it's very important that you get a quick response," said Peter Seeberger, an organic chemistry professor at the Federal Institute of Technology in Zurich, who took part in the research.

"If you are treated within the first 24-48 hours, your chances of survival are good, if not, your chances of dying are 95 percent or greater," he said.

“Until now it has been difficult to create a reliable immunological test -- which detects a substance through its antibody-creating reaction with the immune system -- because the spore cell surface of anthrax is too similar to those of other bacteria.”

"Right now there are antibody-based systems being used in post offices in the U.S.," said Seeberger. "The problem is that anthrax cell surface proteins and those of other closely related bacteria are identical so what you get from the tests are false positives -- so it may be that a harmless bacterium is present but it gives you a positive readout."

A unique carbohydrate comprising four sugar components was discovered on the surface of anthrax spores. Anthrose is the sugar component present in this carbohydrate, which doesn’t exist anywhere else. This was discovered by Seerberger and his team.

Since it was very difficult to isolate that particular sugar from the deadly bacterium, Seeberger and his team thus chose an alternative route: they synthesized the carbohydrate in the laboratory, attached it to a special "carrier" protein and injected this compound into mice.

Usually, carbohydrate antigens bring about weak immunological reaction whereas, this carrier protein stimulated a stable one. Monclonal antibodies were produces and isolated from these immunized mice. These antibodies bound exclusively to the surface molecule of Bacillus anthracis. They did not bind to other bacteria closely related to B. anthracis. Seeberger hoped that a highly sensitive anthrax diagnostic system and new vaccines would be based on this new antibody.

"I think it would be very useful and it could be important for testing against biowarfare," said Seeberger. “The system could be used by the authorities, post offices and medics responding to potential anthrax threats, as well as by armies in the field”, he added.

Seeberger said that it would take 6 months to incorporate these antibodies into the existing systems. Discussions with interested companies were in progress, he said.He hoped for the further development work to be done in Switzerland but it might be done in the United States.

Bacillus anthracis causes the infectious disease Anthrax which usually infects wild and domestic animals such as goats and sheep. Humans can be affected in 3 ways: inhalation of anthrax spores, by eating infected meat that has not been properly cooked and by skin absorption.

"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.”

The online edition of the academic journal Angewandte Chemie (Applied Chemistry) has this study by Swiss scientists published in it.