Genomic epidemiology of Group A Streptococcus in rural Australia

This project focuses on using microbial genomics to identify common antigens among Northern Territory (NT) isolates of Group A Streptococcus (GAS); a bacterial pathogen responsible for skin infections and chronic diseases in Indigenous populations. Indigenous populations within the Northern Territory of Australia are disproportionately affected by Group A Streptococcus. In these remote communities, GAS impetigo prevalences are some of the highest seen in the world, with 40–90% of Indigenous children affected at any one time. A major concern with repeated episodes of GAS impetigo is the potential for GAS to cause post-infection immune-mediated sequalae including Rheumatic Heart Disease (RHD); which is the result of cumulative, permanent damage to the heart valves.

RHD is a chronic, debilitating disease which has no cure and is a major factor responsible for the shorter life expectancy seen in Indigenous compared to non-Indigenous Australians. There is a large inequitable burden of RHD between Indigenous and non-Indigenous Australians. Indigenous Australians are 122 times more likely to develop RHD; and between 20–25 times more likely to die as a result of RHD, than non-Indigenous Australians. The NT Indigenous populations of Australia would therefore greatly benefit from an efficacious GAS vaccine.

The aims of this research project are:
1. Determine the coverage (presence and absence, and allelic distribution) in the NT of the different vaccine antigens that are currently being investigated
2. To then compare our findings of common antigens found among NT isolates to a pool of global isolates; to see if common antigens from the NT are shared between global isolates, or to see if these antigens are exclusive to NT isolates.

This research will provide new information in the field of GAS research and will better help us understand the genetic epidemiology of circulating emm types in Indigenous communities within the NT. This includes furthering our knowledge in the diversity of genetic content; including antigens present in circulating GAS emm types, which could help further develop and enhance non-M based vaccine candidates. Additionally, with this project being a collaboration between the Doherty Institute and Menzies School of Health Research, this project will strengthen relationships between research institutions and will be a platform for future projects.

This project will be a stepping stone in the roadmap to developing a sustainable andefficacious vaccine that provides a high level of protective coverage in Indigenous Australian communities to protect against GAS diseases, particularly RHD; in which Indigenous Australians suffer from an inequitable burden compared to non-IndigenousAustralians.