In pursuit of the lethal agent

You are working at the Centers for Disease Control when blood samples cross your desk taken from patients exhibiting symptoms of anthrax. The patients are related by their place of work, and you suspect a single causative agent.

Obviously, you want to find out what that agent is. You follow the usual routine: attempt to PCR out a region of lef, the gene encoding the lethal factor from Bacillus anthracis. You do this first of all to see if the gene is present. The PCR gives a fragment of the expected size, so there's little doubt about the diagnosis of anthrax.

The second step is to sequence the fragment and compare it against known sequences of the gene, hoping to get clues as to the specific bacterium responsible. You can see the sequence of one of the samples (DG47) by clicking here.

So far, so good. Now to find out which bacterium it belongs to.

     continue