Navigation Links
Clues Found On How Deadly Bacterium Gains Foothold

How a potentially deadly bacterium that could be used as a bioterrorist tool eludes being killed by the human immune system is now better understood, University of Iowa// researchers report in the December issue of the Journal of Leukocyte Biology.

This bacterium, Francisella tularensis, is found naturally in the Northern Hemisphere and can be contracted through certain insect bites, contact with infected rabbits or ingesting contaminated food, water or air.

Francisella tularensis rarely infects people. However, because the bacteria has the potential to be used as a bioterrorist tool there is increased interest in understanding how it functions, said Lee-Ann Allen, Ph.D., associate professor of internal medicine and microbiology at the UI Roy J. and Lucille A. Carver College of Medicine.

"The rate of tularemia or 'rabbit fever' infection has significantly declined since the 1940s. However, the bacteria would be very deadly as an aerosolized terrorist weapon -- inhaling as few as 10 bacteria could be potentially deadly," said Allen, who also is a staff researcher with the Veterans Affairs Iowa City Health Care System.

"We wanted to better understand how Francisella tularensis can overcome the body's innate immune response and cause disease. In addition, learning more about this bacterium can help us learn more about the overall human immune response to bacteria," she said.

The team focused on how Francisella tularensis evades being killed by a form of white blood cells called neutrophils. Normally, neutrophils can be quickly activated in response to infection, making them the equivalent of "first responders" for the human immune system, Allen said.

"We knew that Francisella could live inside other white blood cells called macrophages and not be killed by them," Allen said. "But little research had been done on the bacteria's survival in neutrophils.

"Early data indicated that neutr ophils did not kill Francisella well. With new techniques, many of them more sensitive than in years past, we were able to look at that scenario more closely," Allen added.

The team mixed bacteria with neutrophils taken from healthy volunteers and studied the results.

"We found the neutrophils could ingest the bacteria but were not able to kill them. The Francisella somehow inhibit the ability of the neutrophils to perform two defensive functions that otherwise would kill the bacteria," Allen said.

One of the defensive functions is dependent on oxygen, and the other is oxygen-independent. Ideally, the two functions will be activated and kill the bacteria while they are trapped in a particular compartment within the neutrophils.

"The bacteria prevent these two functions from working in part by blocking the assembly of certain enzymes. After a few hours, the bacteria can escape the compartment instead of being killed, which leaves it able to replicate and cause harm," Allen said.

The researchers now seek to identify how the bacteria prevent neutrophils from mobilizing its defenses and learn more about how those defenses normally function. Additional insights could help with the eventual development of therapies or vaccines against tularemia.

A person infected with tularemia cannot pass the disease on to another person. Hunters are at an increased risk of infection if they skin an infected rabbit. Using blasts of water to clean machines, such as mowers, that have inadvertently come into contact with the carcasses of infected rabbits also can be a risk, as it makes the bacteria easy to inhale.

Allen noted that tularemia infections contracted though the skin are generally less serious to an individual. However, the inhaled form can be fatal if a person does not receive antibiotic treatment.

The Centers for Disease Control and Prevention (CDC) reported an average of 124 suspe cted cases of tularemia in the United States each year from 1990 to 2000, with nearly 60 percent of the cases confirmed. An investigation by the CDC into an outbreak of the disease in 2001 on Martha's Vineyard found that landscapers and gardeners who used power blowers and lawn mowers were at increased risk of being infected.


Related medicine news :

1. Innovative yeast genome may handle Cancer Clues
2. Researchers Discover New Clues To Identify Tooth Decay
3. Leeches Provide Clues Regarding The Prevention Of Heart Disease
4. Excavations Reveal Clues Of Early Warfare
5. Sleeping Computers Yield Clues About Genetic Disorders
6. Clues To Identify Psychological Seizures
7. A Human Brain Gene Could Hold Clues On The Evolution Of Brain Capacity
8. Clues to the Mystery of Lou Gehrigs Disease
9. Clues to Allay Aging
10. Regrowth of Zebrafishs Tail Fin may Offer Clues for Treating Human Injuries
11. Renegade RNA: Clues to Cancer and Normal Growth
Post Your Comments:

(Date:6/25/2016)... ... ... The temporary closing of Bruton Memorial Library on June 21 due to a possible lice ... overlooked aspect of head lice: the parasite’s ability to live away from a human host, ... a necessary one in the event that lice have simply gotten out of control. , ...
(Date:6/25/2016)... ... June 25, 2016 , ... Dr. Calvin Johnson has dedicated ... has implemented orthobiologic procedures as a method for treating his patients. The procedure ... doctors to perform the treatment. Orthobiologics are substances that orthopaedic surgeons use to ...
(Date:6/24/2016)... ... June 24, 2016 , ... Those who have experienced ... feelings, many turn to unhealthy avenues, such as drug or alcohol abuse, as a ... has released tools for healthy coping following a traumatic event. , Trauma sufferers tend ...
(Date:6/24/2016)... (PRWEB) , ... June 24, 2016 , ... Global law ... magazine’s 2016 Legal Elite. The attorneys chosen by their peers for this recognition are ... , Seven Greenberg Traurig Shareholders received special honors as members of this year’s Legal ...
(Date:6/24/2016)... , ... June 24, 2016 , ... People across the ... Genome magazine’s Code Talker Award, an essay contest in which patients and their families ... to be presented at the 2016 National Society of Genetic Counselors (NSGC) Annual Education ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... , June 24, 2016   Pulmatrix, Inc ., ... developing innovative inhaled drugs, announced today that it was ... Investments reconstituted its comprehensive set of U.S. and ... "This is an important milestone for Pulmatrix," said Chief ... shareholder awareness of our progress in developing drugs for ...
(Date:6/23/2016)... 2016 Any dentist who has made an implant ... process. Many of them do not even offer this as ... high laboratory costs involved. And those who ARE able to ... a high cost that the majority of today,s patients would ... Parsa Zadeh , founder of Dental Evolutions Inc. and inventor ...
(Date:6/23/2016)... June 23, 2016 Capricor ... ), a biotechnology company focused on the discovery, ... that patient enrollment in its ongoing randomized HOPE-Duchenne ... exceeded 50% of its 24-patient target. Capricor expects ... third quarter of 2016, and to report top ...
Breaking Medicine Technology: