Molecular epidemiology of Group A Streptococcus in West Africa (acronym: MEGAS)

Dr Annette Erhart, Clinical Epidemiologist
Disease Control & Elimination, MRC Unit The Gambia at LSHTM (The Gambia)
Annette Erhart

Professor Martin Antonio, WHO Collaborating Centre for New Vaccines Surveillance , MRC Unit The Gambia at LSHTM (The Gambia)
Dr Thushan de Silva, Vaccines and Immunity Theme, MRC Unit The Gambia at LSHTM (The Gambia)
Dr Abdul Karim Sesay, Laboratory Service, MRC Unit The Gambia at LSHTM, (The Gambia)
Dr Claire Turner, University of Sheffield (UK)
Professor Pierre Smeesters, Université libre de Bruxelles (ULB) (Belgium)

Group A streptococcus (GAS) causes a massive burden of disease (>500,000 deaths per year), mainly in low- and middle-income countries (LMICs) where Rheumatic Heart Disease (RHD) causes >34 million cases and > 350,000 deaths per year. In May 2018, the WHO passed a resolution on RHD stressing the urgent need to improve prevention strategies, including the development of an effective vaccine. The most advanced multivalent M protein-based vaccine, currently in early clinical development is based on GAS strains found mainly in Europe and USA. In Africa and according to limited information, GAS infections seem to have a much higher genetic diversity of than in high income countries, suggesting that the efficacy of the current 30-valent vaccine may be sub-optimal. However, a recent study in Mali indicated cross-protection between vaccine and non-vaccine serotypes, with a higher-than-expected potential coverage. In order to further inform potential vaccine coverage in Africa, additional information on local GAS strains is urgently needed. This project aims at generating pioneering data on the molecular epidemiology of GAS in West Africa, and at initiating GAS genomic surveillance. Two hundred clinical GAS isolates stored at the MRC Unit The Gambia (MRCG) and 100 prospectively collected samples in Senegal and Burkina Faso will be analysed using whole genome sequencing at the MRCG.  Results will provide invaluable data to further inform current GAS vaccine development, to monitor antimicrobial resistance and to set the scene for upcoming vaccine trials in Africa.