Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Strep bacteria uses a sword and shield to win battle against immune system

21.09.2004


A single gene called cylE within the important bacterial pathogen Group B Streptococcus (GBS), controls two factors that act together as a "sword" and "shield" to protect the bacteria from the killing effects of the immune system’s white blood cells, according to researchers at the University of California, San Diego (UCSD) School of Medicine.



GBS is the leading cause of serious bacterial infections such as meningitis and pneumonia in newborns and is increasingly recognized as a serious pathogen in adult populations, including the elderly, pregnant women and diabetics.

In studies with mice and human blood samples, published in the online edition of Proceedings of the National Academy of Sciences the week of September 20, 2004, the UCSD scientists demonstrated the protective roles of two cylE-encoded factors, one that creates the unusual orange pigmentation of GBS, and another that produces a toxin called hemolysin that kills immune system cells as they surround and attack the bacteria. These findings could lead to new therapeutic approaches that disarm the bacteria and allow the immune system to do its work.


"A crucial part of the body’s defense against bacterial pathogens are white blood cells known as neutrophils and macrophages, which are able to engulf and kill most bacteria" said lead author George Liu, M.D., Ph.D., a UCSD research fellow in pediatric infectious diseases. "We predicted that the GBS bacteria had a unique ability to avoid the killing by white blood cells."

This unique ability turned out to include both the killing effects of the hemolysin toxin, and previously unrecognized antioxidant properties of the GBS orange pigment.

A major weapon that white blood cells use to kill bacteria after engulfment is the production of lethal oxidants similar to peroxide and bleach. Interestingly, the cylE-dependent orange pigment belongs to the family of carotenoids, similar to the compounds that give color to vegetables such as tomatoes and carrots. The anitoxidant properties of food carotenoids have long been touted for their potential health benefits against aging, heart disease and cancer.

"Just as colorful vegetables with antioxidants are touted for their ability to protect us against aging or cancer, we discovered that the GBS bacteria is pulling the same trick to protect itself against our immune system," said the study’s senior author, Victor Nizet, M.D., associate professor, UCSD Division of Infectious Diseases, and an attending physician at Children’s Hospital San Diego.

The UCSD experiments confirmed the importance of the antioxidant role of the orange pigment, as mutant GBS without the cylE gene was 10 to 10,000 times more susceptible to white blood cell oxidants than the disease producing strain.

The new findings are based on previous research by the UCSD group and others, that showed cylE controls the production of hemolysin, as well as the orange pigmentation of the gene. Removal of this gene created a mutant strain of GBS that lacked the hemolysin toxin and was plain white in color. When tested in animal models, the mutant GBS strain was unable to produce serious infections. In the current study, the scientists showed that the mutant GBS strain was rapidly cleared from the bloodstream of experimental animals and more easily killed by purified human and mouse white blood cells.

The hemolysin toxin was the "sword" that poked holes throughout white blood cells, such that in many cases the GBS actually killed the immune cell before it could kill the bacteria. However, even when hemolysin production was inhibited, the GBS continued to survive the white blood cell attack. In additional experiments, the orange pigment was found to be the "shield" that protected the bacteria. Combined, the toxin and orange pigmentation made GBS a potent warrior against white blood cell defenses and consequently a much more lethal pathogen.

"Recognizing the importance of these two properties for GBS infection suggests that novel drug treatments or vaccines that block the hemolysin or disrupt pigment production may be quite effective. Essentially, such therapies could make the GBS bacteria susceptible to elimination by the normal immune system of the newborn infant," Nizet said.

Sue Pondrom | EurekAlert!
Further information:
http://www.ucsd.edu

More articles from Life Sciences:

nachricht Newly designed molecule binds nitrogen
23.02.2018 | Julius-Maximilians-Universität Würzburg

nachricht Atomic Design by Water
23.02.2018 | Max-Planck-Institut für Eisenforschung GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>