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Congratulations to Amy Charbonneau on her publication in mSphere

last modified Jan 12, 2018 11:56 AM

Congratulations to Amelia (Amy) Charbonneau, 2014 cohort PhD student in the BBSRC DTP Programme, for publishing the paper Novel genes required for the fitness of Streptococcus pyogenes in human saliva in mSphere. The paper is the result of a successful collaboration between Amy, primarily based at the Animal Health Trust in the United Kingdom, and colleagues at the Houston Methodist Research Institute in the United States.



Streptococcus pyogenes (group A streptococcus [GAS]) causes 600 million cases of pharyngitis each year. Despite this considerable disease burden, the molecular mechanisms used by GAS to infect, cause clinical pharyngitis, and persist in the human oropharynx are poorly understood. Saliva is ubiquitous in the human oropharynx and is the first material GAS encounters in the upper respiratory tract. Thus, a fuller understanding of how GAS survives and proliferates in saliva may provide valuable insights into the molecular mechanisms at work in the human oropharynx. We generated a highly saturated transposon insertion mutant library in serotype M1 strain MGAS2221, a strain genetically representative of a pandemic clone that arose in the 1980s and spread globally. The transposon mutant library was exposed to human saliva to screen for GAS genes required for wild-type fitness in this clinically relevant fluid. Using transposon-directed insertion site sequencing (TraDIS), we identified 92 genes required for GAS fitness in saliva. The more prevalent categories represented were genes involved in carbohydrate transport/metabolism, amino acid transport/metabolism, and inorganic ion transport/metabolism. Using six isogenic mutant strains, we confirmed that each of the mutants was significantly impaired for growth or persistence in human saliva ex vivo. Mutants with an inactivated Spy0644 (sptA) or Spy0646 (sptC) gene had especially severe persistence defects. This study is the first to use of TraDIS to study bacterial fitness in human saliva. The new information we obtained will be valuable for future translational maneuvers designed to prevent or treat human GAS infections.


Read the full paper.

A podcast concerning this article is available.


Amy is currently identifying better vaccine targets for the prevention of Strangles in the lab of Dr Andrew Waller at the Animal Health Trust. As part of the BBSRC DTP Programme she completed rotation projects at the AHT and in the Department of Veterinary Medicine with Dr Anaid Diaz. Amy recently completed an internship at Entomics Biosystems Ltd.