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Dr Kirsty Le Doare

Institute: St George’s, University of London

Developing a controlled human infection model for Group B Streptococcus

Group B Streptococcus (GBS) is the leading cause of infection in newborn babies, causing approximately 320,000 infections and 90,000 infant deaths globally.

GBS is a common and normally harmless type of bacteria, carried by 20-40% of adults and is usually asymptomatic. Newborns can acquire GBS from their mothers during labour and infection can be life threatening, because their undeveloped immune systems can’t cope with the bacteria.

Group B Streptococcus
Group B Streptococcus.
Image: National Institute of Allergy and Infectious Diseases, National Institutes of Health 

The only prevention currently available to stop transmission is to give pregnant women antibiotics during labour if GBS has been detected during their pregnancy. However, current tests do not always detect the presence of the bacteria, and antibiotics do not always work in any case. A better solution would be a vaccine that could be given to all pregnant women to protect their infants.

To develop an effective vaccine, we need to understand more about the immune response to GBS – particularly the biological factors that affect whether a woman carries GBS in her vagina (bacterial colonisation). We aim to find the factors that protect women from GBS colonisation by asking healthy non-pregnant volunteers to take part in research studies and be purposefully exposed to GBS bacteria, so that we can study their immune reactions.

However, before we start these studies, we need to determine what to measure to characterise vaginal immune responses to GBS. We’re asking women with and without GBS from the UK and Uganda to provide various samples for us to analyse, so we can find the best sampling techniques and gather some preliminary data from women with and without natural infection.  

This preliminary study will be an important step towards a bigger research project to uncover more about GBS colonisation. The long-term goal of our research into GBS immunity is to underpin the development of vaccines to protect infants from potentially fatal GBS infections.    

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