Molecular Horizons - Anuk Indraratna, PhD Exit Seminar

Group A Streptococcus (Strep A) is a globally significant bacterial pathogen, identified as a priority for vaccine development by the World Health Organisation. With case numbers and fatalities continuing to rise, there is an urgent need to improve our understanding of the host-pathogen environment to inform novel therapeutic and prophylactic strategies. In addition to new treatments and an effective vaccine, controlling Strep A will also require modern diagnostic approaches that are sensitive, rapid, and non-invasive.

This seminar details the analysis of human saliva samples following voluntary Strep A infection in a cohort of healthy adults, as part of the Controlled Human Infection for Vaccination Against Streptococcus (CHIVAS) trial. Participants received a controlled dose of bacteria applied directly to the pharynx, and saliva was collected before, during, and after acute throat infection. Salivary proteins were analysed by mass spectrometry to capture changes in the oral environment during pharyngitis, identifying an increase in proteins known: (a) to be implicated in the inflammation response, and (b) to be exploited by Strep A. Independently, carbohydrates (N-glycans) were separately captured and analysed by mass spectrometry, revealing an increase in sialic acid during peak infection. Finally, in conjunction with industry partner Genetic Signatures Limited, these samples were used to establish and validate a novel, highly sensitive, non-invasive saliva qPCR that outperforms the current diagnostic gold standard, aiming to revolutionise the detection of Strep A.