Microarray analysis of the Streptococcus suis serotype 2 transcriptional response to acidic conditions

ABSTRACT: For a pathogen such as Streptococcus suis serotype 2, ecological success is determined by its ability to sense the environment and mount an appropriate adaptive transcriptional response. Thus, determining conditions for analysis of gene expression in vitro that are representative of the in vivo environment is critical for understanding the contributions of transcriptional response pathways to pathogenesis. In this study, we used analysis of the global expression profile in response to acidic pH in vitro and identified a set of regulated genes involved in diverse cellular processes. 196 (11%) genes were differentially regulated by the acid stress: 92 (47%) were down-regulated at low acid (pH 5.8) relative to the neutral condition (pH 7.2), whereas 104 (53%) were up-regulated at pH 5.8 versus pH 7.2. To confirm the microarray data, 16 genes were measured by quantitative RT-PCR. There was a strong positive correlation (r = 0.96) between the results obtained by microarray and quantitative RT-PCR. The data showed that S. suis S2 is equally capable of inducing an acid tolerance response with maximal protection provided after adaptation at pH 5.8 for survival. A cDNA microarray imprinted with 2156 genes representing about 98% of the Streptococcus suis serotype 2 genome was used for transcriptome analysis. For two-sample (reference vs. test) microarray hybridization, four independent bacterial cultures from each condition (pH 5.8, pH 7.2) were prepared as biological replicates for RNA isolation. Accordingly, four dual-fluorescence-labeled cDNA probes were prepared to hybridize with four slides. Pairwise comparisons were made using dye-swaps to avoid labeling bias. A ratio of mRNA levels (test/reference) was calculated for each gene. Significant changes of gene expression were identified with the SAM software. After the SAM analysis, only genes with at least 2-fold changes in expression were collected for further analysis.

ORGANISM(S): Streptococcus suis 05ZYH33

SUBMITTER: Ruifu Yang 

PROVIDER: E-GEOD-21295 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress