ABSTRACT: Relatively little is understood about the dynamics of global hostâpathogen transcriptome changes that occur during bacterial infection of mucosal surfaces. To test the hypothesis that group A Streptococcus (GAS) infection of the oropharynx provokes a host transcriptome response, we performed genome-wide transcriptome analysis using a nonhuman primate model of experimental pharyngitis. We also identified host and pathogen biological processes and individual host and pathogen gene pairs with correlated patterns of expression, suggesting interaction. For this study, 509 host genes and seven biological pathways were differentially expressed throughout the entire 32-day infection cycle. GAS infection produced an initial widespread significant decrease in expression of many host genes, including those involved in cytokine production, vesicle formation, metabolism, and signal transduction. This repression lasted until day 4, at which time a large increase in expression of host genes was observed, including those involved in protein translation, antigen presentation, and GTP-mediated signaling. The interactome analysis identified 73 host and pathogen gene pairs with correlated expression levels. We discovered significant correlations between transcripts of GAS genes involved in hyaluronic capsule production and host endocytic vesicle formation, GAS GTPases and host fibrinolytic genes, and GAS response to interaction with neutrophils. We also identified a strong signal, suggesting interaction between host γδ T cells and genes in the GAS mevalonic acid synthesis pathway responsible for production of isopentenyl-pyrophosphate, a short-chain phospholipid that stimulates these T cells. Taken together, our Q:2 results are unique in providing a comprehensive understanding of the hostâpathogen interactome during mucosal infection by a bacterial pathogen. Longitudinal pharyngeal infection of cynomolgus macaques by group A Streptococcus Briefly, animals were GAS-culture negative and had negligible antistreptolysin O titers, indicating no recent history of GAS exposure. Twenty animals were subjected to a mock-inoculation protocol (PBS only) for 5 weeks, rested for 4 weeks, and inoculated in the upper respiratory tract with 107 CFUsMGAS5005. Blood, saliva, and throat swabs were collected on days 0, 1, 2, 4, 7, 9, 16, 23, 32, 45, 58, 72, and 86. Only the first nine time-points were studied because specimens collected during days 0 to 32 had matching comparator specimens from the mock-infection protocol. Thirty-two clinical and laboratory parameters were measured by the same veterinarian during mock and infection periods. Array data was only for the tonsil swabs, while blood and saliva used for other tests.
