Scientists at the University of Sheffield and the Medical Research Council (MRC) have achieved a breakthrough in understanding natural immunity to Streptococcus pyogenes, commonly known as Strep A, by identifying specific antibodies that protect children against this bacterial infection. The discovery, published in Nature Medicine, could pave the way for developing a vaccine against a pathogen that kills approximately 500,000 people annually worldwide.
Critical Window for Immunity Development
The research team tracked children in The Gambia to understand how natural immunity develops against Strep A. Their findings revealed that while infants are born with maternal protection against the bacteria, this protection quickly fades. However, young children rapidly develop antibody responses to various parts of the bacteria after exposure to Strep A, identifying a critical window for developing immunity that is essential for future vaccine strategies.
"Our findings represent a significant step towards a safe and effective vaccine that could save around half a million lives here in the UK and around the world," said Dr. Alex Keeley, a Wellcome Clinical PhD Fellow in Global Health at the MRC Unit The Gambia and the University of Sheffield's Florey Institute of Infection, who led the research.
Addressing a Global Health Challenge
Strep A primarily causes mild symptoms such as sore throats and flu-like illness, but in more invasive cases, it can be deadly. The infection poses a particularly severe threat in low and middle-income countries, where hundreds of thousands die each year, often due to heart damage resulting from repeated infections. Even in more affluent nations, Strep A can pose serious risks, as demonstrated by a deadly outbreak in the UK and Europe in late 2022 that resulted in more than 400 deaths, including many children.
Fatouamta Camara, a scientist from The Gambia who played a key role in delivering the study, emphasized the local impact: "In The Gambia, Strep A carries a devastating burden on children and adults in their prime years. Beyond causing illness, its impact ripples through families and communities, perpetuating cycles of poverty and reducing quality of life."
Overcoming Historical Barriers
The identification of protective antibodies addresses a fundamental challenge that has long hindered vaccine development. "Historically we have not had the understanding of how people develop natural immunity to Strep A, making the development of a potentially life-saving vaccine incredibly challenging," Keeley explained. "Now, for the first time in humans, we've been able to observe how antibodies that would be made following vaccination may be preventing infections and show how these antibodies may be working against Strep A."
Research Collaboration and Future Directions
The study emerged from a collaboration between the Florey Institute of Infection and GSK Vaccine Institute for Global Health (GVGH), which provided Dr. Keeley with training opportunities in immunoassays - laboratory tests that measure antibodies and other immune responses. This partnership enabled the team to conduct the research at the MRC Unit The Gambia.
Professor Thushan de Silva, Co-Director of the Florey Institute of Infection in Sheffield and a Principal Investigator at the MRC Unit The Gambia, who supervised the research, noted: "This study reflects the value of working across institutions to deliver high-quality and impactful research in global health."
The researchers hope their findings will lead to vaccine trials in different parts of the world to ultimately prove that vaccines can provide safe and effective protection against Strep A, offering hope for preventing hundreds of thousands of deaths annually and improving health outcomes for children and communities worldwide.
