Longitudinal analysis of the group A Streptococcus transcriptome in experimental pharyngitis in cynomolgus macaques - PubMed (original) (raw)

. 2005 Jun 21;102(25):9014-9.

doi: 10.1073/pnas.0503671102. Epub 2005 Jun 14.

Stephen F Porcella, Morag R Graham, Robin M Ireland, Claire A Johnson, Stacy M Ricklefs, Imran Babar, Larye D Parkins, Romina A Romero, G Judson Corn, Don J Gardner, John R Bailey, Michael J Parnell, James M Musser

Affiliations

Longitudinal analysis of the group A Streptococcus transcriptome in experimental pharyngitis in cynomolgus macaques

Kimmo Virtaneva et al. Proc Natl Acad Sci U S A. 2005.

Abstract

Identification of the genetic events that contribute to host-pathogen interactions is important for understanding the natural history of infectious diseases and developing therapeutics. Transcriptome studies conducted on pathogens have been central to this goal in recent years. However, most of these investigations have focused on specific end points or disease phases, rather than analysis of the entire time course of infection. To gain a more complete understanding of how bacterial gene expression changes over time in a primate host, the transcriptome of group A Streptococcus (GAS) was analyzed during an 86-day infection protocol in 20 cynomolgus macaques with experimental pharyngitis. The study used 260 custom Affymetrix (Santa Clara, CA) chips, and data were confirmed by TaqMan analysis. Colonization, acute, and asymptomatic phases of disease were identified. Successful colonization and severe inflammation were significantly correlated with an early onset of superantigen gene expression. The differential expression of two-component regulators covR and spy0680 (M1_spy0874) was significantly associated with GAS colony-forming units, inflammation, and phases of disease. Prophage virulence gene expression and prophage induction occurred predominantly during high pathogen cell densities and acute inflammation. We discovered that temporal changes in the GAS transcriptome were integrally linked to the phase of clinical disease and host-defense response. Knowledge of the gene expression patterns characterizing each phase of pathogen-host interaction provides avenues for targeted investigation of proven and putative virulence factors and genes of unknown function and will assist vaccine research.

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Figures

Fig. 1.

Fig. 1.

Five medical parameters used in expression analysis of GAS PHG. Each parameter is depicted by two-way ANOVA plot, with the measurement on the y axis and the sample collection day of the study on x axis. The infection phase (days 0–86) is marked with a red line, and the mock phase (days 0–32) is labeled brown. SEM is indicated by error bars. (A) GAS colony count as measured from tonsillar throat swabs (CFU). (B) Percentage of polymorphonuclear leukocytes in peripheral venous blood (SEGS). (C) C-RP levels in blood (mg/liter; C-RP). (D) TON score on a scale of 1–4. (E) PHG severity score on a scale of 0–3 (PHG). Colonization and asymptomatic carriage phases are indicated by gray shading.

Fig. 2.

Fig. 2.

Functional category analysis of GAS gene expression data. GAS CFU were plotted on the y axis, and the study day was plotted on the x axis. The infection phase (days 0–86) is indicated by a red line, and the mock phase (days 0–32) is labeled in brown. Number of GAS genes belonging to 17 functional categories were plotted based on their correlation with GAS CFU. Genes having positive (+Z) or negative (–Z) expression correlation with GAS CFU are shown by histograms at three phases. Colonization and asymptomatic carriage phases are indicated by gray shading.

Fig. 3.

Fig. 3.

TaqMan RNA quantitative PCR (Q-PCR) confirmation of expression of GAS SAgs involved in inflammation (smeZ, speA2, and speJ), complement resistance regulon (mga, emm1, sic, and scpA), and TCS regulation (covR and spy0680/M1_ spy0874). Induction of strain MGAS5005 prophage (Φ1, Φ2, and Φ3) as confirmed by TaqMan DNA Q-PCR. Bars indicate time points at which the level of RNA or DNA is at least 1.25-fold or greater than mean expression level. Clinical parameters for GAS CFU (red), PHG (blue), and TON (purple) are shown. Colonization and asymptomatic carriage phases are indicated by gray shading.

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