Nav: Home

New findings on killer bacteria's defence

December 14, 2012

Antibodies are key to the recognition and neutralisation of bacteria by our immune system. The most common antibodies have the shape of a Y, and the two prongs fasten to molecules that belong to the bacteria. The cells in the immune system recognise the shaft and can then attack the bacteria.

Since the 1960s, it has been known that certain bacteria have developed the ability to turn these antibodies around, which makes it more difficult for the immune system to identify them. These include streptococcus bacteria, sometimes referred to as 'killer bacteria', that cause both common tonsillitis and more serious diseases such as sepsis (blood poisoning) and necrotising fasciitis (flesh-eating disease). Because it has not been possible to study this phenomenon in detail, researchers have until now presumed that antibodies are always turned around in these streptococcal infections.

Now researchers at Lund University have shown that this is not the case. In less serious conditions, such as tonsillitis, the antibodies are back-to-front, but in more serious and life-threatening diseases such as sepsis and necrotising fasciitis, the antibodies are the right way round. These findings have now been published in the Journal of Experimental Medicine and completely alter the understanding of bacterial infections with several of our most common pathogenic bacteria.

"This information is important and fundamental to improving our understanding of streptococcal infections, but our results also show that the principle described could apply to many different types of bacteria", says Pontus Nordenfelt, who is currently conducting research at Harvard Medical School in Boston.

The present study shows that it is the concentration of antibodies in the local environment in the body that controls how the antibodies sit on the surface of the bacteria. In the throat, for example, where the concentration is low, the antibodies sit the wrong way round, but in the blood, where the concentration is high, the antibodies are the right way round. This explains why the most serious infections are so rare in comparison to the common and often mild cases of throat and skin infections.

The bacteria in the blood are quite simply easier for the immune system to find.

In the future, the results could have an impact on the treatment of serious infectious diseases, since a better understanding of the mechanisms behind the diseases is needed to develop new treatments.

Lars Björck, Professor of Infectious Medicine at Lund University, has discovered some of the antibody-turning proteins and has studied their structure and function for over 30 years.

"It is fantastic to have been involved in moving a major step closer to understanding the biological and medical importance of these proteins together with talented young colleagues", he says.
-end-
For more information:

Pontus Nordenfelt, pontus.nordenfelt@childrens.harvard.edu, telephone: +1 857 225 3050

Link to article in the Journal of Experimental Medicine

'Antibody orientation at bacterial surfaces is related to invasive infection'. Pontus Nordenfelt, Sofia Waldemarson, Adam Linder, Matthias Mörgelin, Christofer Karlsson, Johan Malmström and Lars Björck. The Journal of Experimental Medicine.

Lund University

Related Immune System Articles:

Using the immune system as a defence against cancer
Research published today in the British Journal of Cancer has found that a naturally occurring molecule and a component of the immune system that can successfully target and kill cancer cells, can also encourage immunity against cancer resurgence.
First impressions go a long way in the immune system
An algorithm that predicts the immune response to a pathogen could lead to early diagnosis for such diseases as tuberculosis
Filming how our immune system kill bacteria
To kill bacteria in the blood, our immune system relies on nanomachines that can open deadly holes in their targets.
Putting the break on our immune system's response
Researchers have discovered how a tiny molecule known as miR-132 acts as a 'handbrake' on our immune system -- helping us fight infection.
Decoding the human immune system
For the first time ever, researchers are comprehensively sequencing the human immune system, which is billions of times larger than the human genome.
Masterswitch discovered in body's immune system
Scientists have discovered a critical part of the body's immune system with potentially major implications for the treatment of some of the most devastating diseases affecting humans.
How a fungus can cripple the immune system
An international research team led by Professor Oliver Werz of Friedrich Schiller University, Jena, has now discovered how the fungus knocks out the immune defenses, enabling a potentially fatal fungal infection to develop.
How the immune system protects us against bowel cancer
Researchers from Charité - Universitätsmedizin Berlin have discovered a protective mechanism which is used by the body to protect intestinal stem cells from turning cancerous.
How herpesviruses shape the immune system
DZIF scientists at the Helmholtz Zentrum München have developed an analytic method that can very precisely detect viral infections using immune responses.
The immune system's fountain of youth
Helping the immune system clear away old cells in aging mice helped restore youthful characteristics.
More Immune System News and Immune System Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.