Unmasking anthrax for immune destruction

April 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 to new measures to treat anthrax infection in the event of a biological warfare attack.

Bacillus anthracis is a particularly lethal pathogen because it manages to escape recognition by the host's immune system by coating itself with a protective capsule around its surface. A key bacterial enzyme called capsule depolymerase (CapD) anchors the capsule to the cell surface. CapD can also cut and release some of the capsule into small fragments that are thought to interfere with specific parts of the immune system, offering further protection to the bacterium.

Scientists at the U.S. Army Medical Research Institute of Infectious Diseases discovered that by engineering B. anthracis to produce higher-than-normal amounts of CapD, the protective capsule is chopped up and released as tiny fragments. The bacterium is left nearly completely unmasked and therefore vulnerable to immediate detection and destruction by the macrophage and neutrophil 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 principal investigators in the study.

B. anthracis is the most commonly mentioned pathogen associated with biological warfare. This bacterium can form resilient spores that survive dormant in the environment for long periods of time. When these spores are aerosolised the bacterium can be very effectively distributed. After human inhalation the spores reactivate and cause severe infection that is usually fatal if left untreated.

Dr Friedlander believes his groups' findings could have significant clinical impact. "Many pathogenic bacteria, 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 in the event of a biological attack."

Finding a way to encourage B. anthracis to unwittingly unmask itself, using the bacterium's own machinery would be a novel approach to eradicating the pathogen. "What is more, these measures may also be effective against strains of B. anthracis that have been genetically engineered to be resistant to antibiotics and/or existing vaccines," suggested Dr. Friedlander.
-end-


Microbiology Society

Related Immune System Articles from Brightsurf:

How the immune system remembers viruses
For a person to acquire immunity to a disease, T cells must develop into memory cells after contact with the pathogen.

How does the immune system develop in the first days of life?
Researchers highlight the anti-inflammatory response taking place after birth and designed to shield the newborn from infection.

Memory training for the immune system
The immune system will memorize the pathogen after an infection and can therefore react promptly after reinfection with the same pathogen.

Immune system may have another job -- combatting depression
An inflammatory autoimmune response within the central nervous system similar to one linked to neurodegenerative diseases such as multiple sclerosis (MS) has also been found in the spinal fluid of healthy people, according to a new Yale-led study comparing immune system cells in the spinal fluid of MS patients and healthy subjects.

COVID-19: Immune system derails
Contrary to what has been generally assumed so far, a severe course of COVID-19 does not solely result in a strong immune reaction - rather, the immune response is caught in a continuous loop of activation and inhibition.

Immune cell steroids help tumours suppress the immune system, offering new drug targets
Tumours found to evade the immune system by telling immune cells to produce immunosuppressive steroids.

Immune system -- Knocked off balance
Instead of protecting us, the immune system can sometimes go awry, as in the case of autoimmune diseases and allergies.

Too much salt weakens the immune system
A high-salt diet is not only bad for one's blood pressure, but also for the immune system.

Parkinson's and the immune system
Mutations in the Parkin gene are a common cause of hereditary forms of Parkinson's disease.

How an immune system regulator shifts the balance of immune cells
Researchers have provided new insight on the role of cyclic AMP (cAMP) in regulating the immune response.

Read More: Immune System News and Immune System Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.