Analysis of vaccine antigen expression in a diverse collection of Streptococcus pyogenes isolates

Summary 

Streptococcus pyogenes, also known as group A streptococcus or Strep A, causes over half a million deaths annually by triggering rheumatic heart disease and further deaths due to serious invasive infections such as sepsis and flesh-eating infections. These deaths could be prevented if there was a vaccine against Strep A. In 2018, the World Health Organisation (WHO) identified Strep A as a priority for vaccine development. For a vaccine to work as well as possible, it needs to raise an immune response against a target that is made by all strains of Strep A, made in large amounts, and ideally is located on the surface of the bacteria so that cells of the immune system can effectively find and destroy bacteria in the body. There are a few Strep A vaccines currently being developed that share targets. We have developed a test to measure the amount of each target on the surface of the Strep A bacteria that uses a tagging system known as fluorescence. We will use this test on strains of Strep A from sore throats and skin infections from London, UK, and Sukuta, the Gambia, to measure how much of each antigen is on the surface of these bacteria. This will help us predict how well the vaccines in development would protect against Strep A in different parts of the world. This will help us decide which vaccine would best protect against Strep A across the whole globe.