Flinders Medical Centre Foundation
Flinders Medical Centre Foundation

Immune System

How Bacteria Defeats The Immune System
First Published: Investigator - October 2005

Professor David Gordon, Head of the Department of Microbiology and Infectious Diseases, and his team of researchers at Flinders are endeavouring to understand how a particular strain of bacteria is able to escape the body’s immune system.

The streptococci bacteria is commonly found in the throat or skin and while harmless to some, others can experience a range of mild symptoms such as tonsillitis to the severe symptoms associated with the Group A strain.

Group A Streptococcus is potentially an extremely aggressive organism whose effects can lead to overwhelming infection such as disease of vital organs, rheumatic fever and destruction of the skin and soft tissues, better known as “flesh eating disease”.

Diseases of the kidneys and heart associated with this bacterium can develop due to tissue damage directly caused by reactions of the immune system. For example, proteins within this strain of bacteria are very similar to those found within the heart valves. When the body is under threat by Group A Streptococcus the immune system attempts to kill this bacteria, unfortunately also attacking the healthy proteins within the heart.

Dr Gordon and his team are working at a molecular level, focusing on how the Group A Streptococcus works its escape from the body’s immune system.

So far Dr Gordon and his team have found that part of this harmful bacterium binds a specific part of the body’s immune defences, the complement system, rendering it unable to kill this bacteria as it normally would. The team has also identified a receptor on human cells that allows this bacterium to attach to the skin and throat.

“The reason it is so important we understand how bacteria escapes the immune system is so better targets for vaccines can be identified and alternative preventions and treatments devised,” says Dr Gordon. “It is also relevant to our knowledge of how the immune system operates and for understanding how other or new strains of bacteria might cause disease.”

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