Identifying genetic determinants of Streptococcus pyogenes-host interactions in a murine intact skin infection model

Streptococcus pyogenes is an obligate human pathobiont associated with many disease states. Here, we present a novel model of S. pyogenes infection using intact murine epithelium. From this model, we were able to perform RNA sequencing to evaluate the genetic changes undertaken by both the bacterium and host at 5 and 24 hours post infection. Analysis of these genomic data demonstrate that S. pyogenes undergoes significant genetic adaptation to successfully infect the murine epithelium, including changes to metabolism and activation of the Rgg2/Rgg3 quorum sensing (QS) system. Subsequent experiments demonstrate that an intact Rgg2/Rgg3 QS cascade is necessary to establish a stable superficial skin infection. Furthermore, activation of this pathway results in increased murine morbidity and increased bacterial burden on the skin. This phenotype is associated with gross changes to the murine skin, as well as histopathological evidence of inflammation. Taken together, these experiments offer a novel method to investigate S. pyogenes-epithelial interactions and demonstrate that a well-studied QS pathway is critical to a persistent infection. Overall design: To investigate gene expression assoicated with infection of intact murine skin by Streptococcus pyogenes, we obtained RNA from both mice and bacterium at 5 and 24 hours after infection. Dual RNAsequencing allowed for comparison of bacterial samples to their input control, as well as murine samples versus their uninfected control.