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 Study shines light on brain cells that coordinate movement
26.06.2017 | University of Washington Health Sciences/UW Medicine

nachricht New insight into a central biological dogma on ion transport
26.06.2017 | Aarhus University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Study shines light on brain cells that coordinate movement

26.06.2017 | Life Sciences

Smooth propagation of spin waves using gold

26.06.2017 | Physics and Astronomy

Switchable DNA mini-machines store information

26.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>