Diagnosing the plague

A dipstick test for plague on the way

Plague could soon be
diagnosed fasterthan ever before, thanks to scientists in Germany.

The team, led by Peter Seeberger from the Max Planck Institute of Colloids and Interfaces in Potsdam, isolated an antibody which specifically recognisesYersinia pestis (Y. pestis), the bacterium responsible for plague. This paves the way for a dipstick test which could identify the bacterium in minutes.

The idea of using an antibody to detect bacteria is not new: such devices are available for malaria and HIV, for example. Antibodies recognise bacteria by their antigens, unique markers in their cell wall, to which they bind to destroy the intruder.

The team identified and synthesised a heptose trisaccharide antigen that is specific toY. pestis, then injected it into mice. The mice made cooresponding antibodies, which the team isolated and purified. Test showed that they bound strongly toY. pestis, and not to similar Gram-negative bacteria such asEscherichia coliandNeisseria meningitidis.

Y. pestisis considered one of the deadliest bacteria in human history - it is estimated that the Black Death killed between a third and half of the population of Europe. Nowadays the three strains of plague - septicaemic, pneumonic and bubonic - are all treatable with a powerful course of antibiotics, but are usually fatal if left unchecked.

While recent outbreaks have not been on the scale of the pandemics of yesteryear, there are still 1000-2000 cases annually, mostly in sub-Saharan Africa and the developing world. These cases have been difficult to catch as conventional diagnostic methods rely on slow, complex and expensive techniques, meaning blood samples would have to be sent to a laboratory. Not only are such facilities limited in isolated areas, but in many cases the time needed for such tests is all the time the disease needs to kill its victim.

Now that the team has identified a carbohydrate that is unique to the surface ofY. pestisand expressed the corresponding antibody, it can be incorporated into a diagnositc device like a pregnancy test kit. The team is currently looking for partners to develop the device.