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Dr Alice Halliday

Institute: University of Bristol

Gene expression profiling of candidate vaccine antigens of group A streptococcus (GAS) in the upper airways during natural infection, after infectious challenge and during viral co-infection

Group A streptococcus (GAS) is a type of bacterium that causes a wide range of conditions in people, from mild to potentially life threatening.

Group A Streptococcus
Group A Streptococcus on a human neutrophil
Image: National Institute of Allergy and Infectious Diseases, National Institutes of Health

The most common infection caused by GAS bacteria is pharyngitis, also known as ‘strep throat’, which usually affects children and teenagers. In most cases, the infection clears up by itself or with antibiotics after a few days. However, a small proportion of people infected with GAS develop severe diseases and complications, such as rheumatic fever and rheumatic heart disease, scarlet fever, so-called flesh-eating disease or dangerous blood infections.

There is currently no vaccine available to prevent symptoms caused by GAS infection, although work is underway by scientists and companies in several countries to develop one. The benefits of a vaccine would be two-fold; reducing both the burden of GAS-related diseases and the use of antibiotics for throat infections (which would help slow down the development of antibiotic resistance).    

However, development of a vaccine is being held back by our limited understanding of the biology of GAS infection in people. Our research aims to speed up vaccine development by characterising what happens during infection in the nose and throat of people, in order to find the best part/s of the GAS bacterium to use in a vaccine.

To do this, we are currently developing a tool to measure which genes are switched on and off when GAS infects people, and studying the differences between mild and severe infections. We also want to compare responses in volunteers who took part in studies where they were purposefully exposed to GAS bacteria in a controlled way to people who naturally contracted the infection. 

The findings from this work will help to support current and future research programmes to develop an effective vaccine against GAS infection and the diseases it causes.

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