Deadly microbe dodges human immune system

by Dr Tim Barnett
Deadly microbe dodges human immune system
Group A Streptococcus (green) shown to be growing inside of a cell (red, caputured by a fluorescence microscope).

Scientists from The University of Queensland have discovered that a microbe responsible for invasive bacterial Group A Streptococcus infections can bypass the immune system and multiply within infected cells.

Group A Streptococcus is one of the world's most fatal , with 600,000 cases annually.

In December last year a statewide alert was issued to all doctors and hospitals after a four-year-old child died from Group A Streptococcal disease in Brisbane.

Research leader Dr Tim Barnett from UQ's School of Chemistry and Molecular Biosciences said the findings were significant because they contradicted previous understandings of how the bacteria behaved.

"We studied M1T1, one of the most prevalent strains affecting the developed world," Dr Barnett said.

"It had previously been thought that autophagy, which is part of the , efficiently defended the interior of cells against Group A Streptococcus."

He said the research showed that in fact M1T1 produced an enzyme that breaks down the patient's immune proteins that fight bacterial infection.

"Our findings were vastly different to previous studies that used strains not commonly associated with human disease," Dr Barnett said.

"We now know that Streptococcus can hide, survive and grow in cells."

Dr Barnett is part of Professor Mark Walker's research group.

He and other colleagues at the Australian Infectious Diseases Research Centre are using this discovery to continue investigations in the field.

The research is also relevant to a number of types of Group A Streptococcus, including M12 strain found in a recent outbreak of scarlet fever in Hong Kong.

More information: Timothy C. Barnett, David Liebl, Lisa M. Seymour, Christine M. Gillen, Jin Yan Lim, Christopher N. LaRock, Mark R. Davies, Benjamin L. Schulz, Victor Nizet, Rohan D. Teasdale, Mark J. Walker, "The Globally Disseminated M1T1 Clone of Group A Streptococcus Evades Autophagy for Intracellular Replication," Cell Host & Microbe, Volume 14, Issue 6, 11 December 2013, Pages 675-682, ISSN 1931-3128, dx.doi.org/10.1016/j.chom.2013.11.003.

Related Stories

Scientists reveal steps leading to necrotizing fasciitis

Jan 16, 2014

How does Streptococcus pyogenes, or Group A streptococcus (GAS)—a bacterial pathogen that can colonize humans without causing symptoms or can lead to mild infections—also cause life-threatening diseas ...

Typhoid Fever: A race against time

Jan 16, 2014

The life-threatening disease typhoid fever results from the ongoing battle between the bacterial pathogen Salmonella and the immune cells of the body. Prof. Dirk Bumann's research group at the Biozentrum ...

Strep infections responsible for groper deaths

Jul 20, 2011

Researchers are in a race against time to save Queensland's protected groper fish, which are washing up dead along the beaches of Northern Queensland in increasing numbers.

Genome blueprint for horse and human vaccines

Jul 14, 2011

Two strains of Streptococcus bacteria, that have evolved to cause potentially fatal infections in either horses or humans, use the same box of tricks to cause disease. Exploiting their genetic similarities could ...

Recommended for you

UN says Syria vaccine deaths was an NGO 'mistake'

10 hours ago

The recent deaths of Syrian children after receiving measles vaccinations was the result of a "mistake" by a non-governmental partner who mixed in a muscle relaxant meant for anesthesia, a spokesman for the U.N. secretary-general ...

First US child dies from enterovirus D68

11 hours ago

A child in the northeastern US state of Rhode Island has become the first to die from an ongoing outbreak of a respiratory virus, enterovirus D68, health officials said Wednesday.

US Ebola patient had contact with kids: governor

11 hours ago

A man who was diagnosed with Ebola in virus in Texas came in contact with young children, and experts are monitoring them for any signs of disease, governor Rick Perry said Wednesday.

UN worker dies of suspected Ebola in Liberia

12 hours ago

The United Nations mission in Liberia announced on Wednesday the first suspected victim among its employees of the deadly Ebola epidemic ravaging the impoverished west African nation.

User comments