Overcoming anthrax bacterium's natural defenses could hold key to new treatments

May 18, 2010

Army scientists have discovered a way to "trick" the bacterium that causes anthrax into shedding its protective covering, making it easier for the body's immune system to mount a defense. The study, which appears in this month's issue of the journal Microbiology, could lead to new approaches for treating anthrax infection.

, the causative agent of anthrax, is particularly lethal because of its protective coating, or capsule, which enables the pathogen to escape destruction by the host's immune system. A key called capsule depolymerase, or CapD, anchors the capsule to the cell surface. CapD also cuts and releases part of the capsule into small fragments that are thought to interfere with specific parts of the immune system, offering further protection to the bacterium. The rest of the capsule remains intact.

Finding a way to cause B. anthracis to unmask itself, using the bacterium's own machinery, would be a novel approach to defeating the pathogen. So scientists at the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) induced B. anthracis to make higher-than-normal amounts of CapD, resulting in release of the capsule fragments. This left very little capsule attached to the . As a result, the unprotected bacteria were left vulnerable to immediate detection and destruction by the cells of the immune system.

"By engineering B. anthracis to over-produce CapD, we are effectively turning the bacterium's own weapon on itself," explained Dr. Arthur Friedlander, one of the study's principal investigators. He believes the USAMRIID group's findings could have significant clinical impact.

"Many , including B. anthracis, produce a capsule surrounding them that prevents the infected host from killing them, improving their chances of causing disease," he explained. "Understanding the mechanisms of virulence used by the anthrax bacterium is vital to developing medical countermeasures against it."

Anthrax most commonly occurs in wild and domestic mammals, although it has the potential to be used as a biological threat agent. Symptoms vary depending on the route of exposure; however, mild fever, fatigue and muscle aches usually begin within 4-6 days of exposure. As the bacteria multiply in the lymph nodes, toxemia progresses and the potential for widespread tissue dissemination, destruction and organ failure increases. Severe breathing difficulty, meningitis and shock can follow. Up to 90 percent of untreated cases of inhalational anthrax result in death.

"This study provides significant insight into the pathogenesis of anthrax infection, tracing the connection between B. anthracis gene expression to its effect on host response," said Colonel John P. Skvorak, commander of USAMRIID.

Explore further: Genomes of malaria-carrying mosquitoes sequenced

Provided by US Army Medical Research Institute of Infectious Diseases

5 /5 (1 vote)
add to favorites email to friend print save as pdf

Related Stories

Unmasking anthrax for immune destruction

Apr 30, 2010

Anthrax-causing bacteria can be engineered to shed their invisibility cloaks, making it easier for the immune system to eradicate it, according to a new study published in Microbiology. The work could lead t ...

Researchers image crucial anthrax protein

Jul 14, 2009

(PhysOrg.com) -- Anthrax, long feared for its potential as a biological weapon, has lost some of its mystery. Researchers at the U.S. Department of Energy's (DOE) Argonne National Laboratory, in collaboration ...

A faster, more sensitive method for detecting anthrax

Nov 05, 2007

Amid continuing concerns that anthrax might be used as a bioterrorism weapon, government researchers report development of a faster, more sensitive blood test for detecting the deadly toxins produced by the ...

Anthrax cellular entry point uncovered

Jan 25, 2008

The long-sought-after biological “gateway” that anthrax uses to enter healthy cells has been uncovered by microbiologists at the University of Alabama at Birmingham (UAB).

Recommended for you

Genomes of malaria-carrying mosquitoes sequenced

9 hours ago

Nora Besansky, O'Hara Professor of Biological Sciences at the University of Notre Dame and a member of the University's Eck Institute for Global Health, has led an international team of scientists in sequencing ...

How calcium regulates mitochondrial carrier proteins

Nov 26, 2014

Mitochondrial carriers are a family of proteins that play the key role of transporting a chemically diverse range of molecules across the inner mitochondrial membrane. Mitochondrial aspartate/glutamate carriers are part of ...

Team conducts unprecedented analysis of microbial ecosystem

Nov 26, 2014

An international team of scientists from the Translational Genomics Research Institute (TGen) and The Luxembourg Centre for Systems Biomedicine (LCSB) have completed a first-of-its-kind microbial analysis of a biological ...

Students create microbe to weaken superbug

Nov 25, 2014

A team of undergraduate students from the University of Waterloo have designed a synthetic organism that may one day help doctors treat MRSA, an antibiotic-resistant superbug.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.