Original text: Nature Science Update at http://www.nature.com/nsu/011004/011004-12.html

Black Death's DNA

...Researchers have sequenced the plague bacterium's genome1. The 4.65 million DNA letters will be "the basis of all future work", on plague, says Julian Parkhill of the Sanger Centre, Cambridge, UK, who led the sequencing project. The sequence will be critical in the design of antibiotics and vaccines to treat the disease. It is a yardstick against which potential new plague threats - whether created by natural selection or as biowarfare agents - can be measured. It will also teach us a great deal about how infectious diseases evolve. The plague bacterium Yersinia pestis is a recent descendent of the benign, gut-dwelling bug Y. pseudotuberculosis. "Two thousand years ago it gave you a mild tummy ache," says team member Brendan Wren, a geneticist at the London School of Hygiene and Tropical Medicine.