for National Geographic Today
Scientists have figured out how anthrax invades the cell and how it
disrupts communication within the immune system eventually leading to
death. The findings were revealed at a press conference yesterday in
Washington, D.C.
The new anthrax findings are examples of
"extraordinary, elegant science," said Anthony Fauci, director of the
National Institute of Allergy and Infectious Diseases. He believes the
new findings may be instrumental in fighting the disease in its advanced
stages; antibiotics such as Cipro are effective only if administered
soon after a person becomes infected.
"You can't rush the science, but when the science points you in the right direction then you can start rushing," says Fauci. Now is the time to translate these findings into something that is useful to public health, he added.
Anthrax research has been thrust into the spotlight since the terrorist attacks of September 11 and even more so since the letters containing a highly toxic form of the bacterium were mailed to journalists and politicians in New York and Washington.
"If you don't kill the anthrax bacterium soon after infection, the microbe has time to produce potentially fatal levels of toxin, against which current drugs are not likely to be effective," said Fauci.
Killing anthrax requires two bullets: one to kill the bacterium and one to block the toxic proteins it produces. As far as killing the bacterium goes antibiotics are effective.
Simply speaking, the anthrax bacterium is a factory that multiplies in the blood stream and continuously pumps out three different toxins. The toxins attack white blood cells—critical defenders against bacterial foes—disarming the body's immune system so that the bacteria may reproduce unhindered.
One of the three toxins produced by anthrax functions like a scout and gatekeeper—it seeks white blood cells and locates a docking port on the cell where it attaches itself. It then creates an entrance for the other two toxins to invade the cell.
But the toxin molecule cannot enter a cell just anywhere. The good news announced Tuesday is that researchers have discovered the specific door, or receptor, that the toxin uses to enter a white blood cell. The receptor, called anthrax toxin receptor (ATR), is the docking site for one part of the toxin.
Once the door is opened the two other toxins enter the cell and essentially sever communication with all other parts of the immune system. Inside the white blood cell, the toxin known as "lethal factor" grabs its target, cutting a critical bond on a single molecule within the cell. The crippled cell is no longer able to communicate with the rest of the immune system.
John Collier of Harvard University in Cambridge, Massachusetts and John Young of the University of Wisconsin in Madison led the work which has been published online by the journal Nature.
