Protein Found That Explodes Anthrax Bacteria on Contact

NEW YORK, New York, April 21, 2006 (ENS) - A protein that can fight dreaded anthrax infections and decontaminate large areas where anthrax spores have been released as a bioweapon has been discovered by scientists at Rockefeller University.

The protein was identified by Vincent Fischetti, professor and co-head of the Laboratory of Bacterial Pathogenesis and Immunology at Rockefeller, who has been studying bacteria, including anthrax-related organisms, for the past 45 years. His results are published in the April issue of the "Journal of Bacteriology."

“Anthrax is the most efficient biowarfare agent," said Fischetti. "Its spores are stable and easy to produce, and once someone inhales them, there is only a 48 hour window when antibiotics can be used."


Years of research have paid off for Rockefeller University Professor Vincent Fischetti. He discovered a protein that attacks the deadly bioweapon anthrax. (Photo courtesy Rockefeller U.)
“We’ve found a new protein that could both potentially expand that treatment window and be used as a large-scale decontaminant of anthrax spores,” Fischetti said.

Because it is deadly, noncontagious, and dispersed by spores, anthrax is considered a good candidate for a bioweapon. Late in 2001, letters containing anthrax spores were sent to several U.S. news reporters and two U.S. senators.

Five people died of inhalational anthrax as a result, about 24 people developed infections, and many more were exposed, but were treated in time to avoid becoming ill.

The culprit has never been found.

Now, Fischetti and his team intend to mix their newly found protein into a solution that could be used in buildings, on transportation equipment, on clothing, even on skin, providing a safe, easy way to fight the spread of anthrax in the event of a mass release.

All bacteria, anthrax included, have natural predators called bacteriophage, Fischetti explains. Just as viruses infect people, bacteriophage infect bacteria, reproduce, and then kill their host cell by bursting out to find their next target.

The bacteriophage use special proteins, called lysins, to bore holes in the bacteria, causing them to explode.

In 2004, Fischetti and colleagues identified one of these lysins, called PlyG, and showed that it could be used to help treat animals and humans infected by anthrax.

They now have identified a second lysin, which they have named PlyPH, with special properties that make it a good therapeutic agent and useful for large-scale decontamination of areas like buildings and military equipment.

The new protein has several advantages. Most lysins, including PlyG, are only active in a very specific pH range of six to seven, so that they work effectively in the human bloodstream, but may not be useful in many environmental conditions.

“PlyPH works in an extremely wide pH range, from as low as four to as high as eight,” says Fischetti. “I don’t know of any other lytic enzyme that has such a broad range of activity.”


A bacillus bacterium, a close relative of anthrax, begins to explode after being treated with the PlyPH protein. (Photo courtesy Rockefeller U.)
Both lysins are highly specific in terms of the types of bacteria they kill.

When Fischetti and colleagues added PlyPH to different bacterial species, only the anthrax bacteria were killed.

This is a great benefit over antibiotics, which kill many different bacteria, including many helpful species.

Anthrax is resistant to many of the antibiotics currently available to treat it, but because PlyPH is so specific, anthrax is not likely to develop resistance to it, the researchers said.

“We have never seen bacterial resistance to a lysin,” says Fischetti. “PlyPH and PlyG are probably the most specific lysins we, or anyone, has ever identified. They only kill anthrax and its very close relatives."

"This feature, and the wide pH range offered by PlyPH, is why we think it could be used as an environmental decontaminant,” he said.

Fischetti hopes to create a solution based on the newly found protein that would be a powerful tool for cleaning up after an anthrax attack.

The PlyPH protein would be combined with a non-toxic aqueous substance developed by a group in California that will germinate any anthrax spores it touches. As the spores germinate, the solution would kill them on contact within minutes.