Microarray Analysis of Temperature-induced Transcriptome of Streptococcus suis serotype 2

Streptococcus suis serotype 2 (SS2) is able to cause human infections ranging from superficial wounded skin infections to severe invasive infections such as meningitis and streptococcal toxic shock-like syndrome (STSLS). During its infection cycle, SS2 must acclimatize itself to temperature shift. Herein, a whole-genome DNA microarray was used to investigate the global transcriptional regulation of an invasive SS2 strain grown to late-exponential phase at 29 or 40°C relative to 37°C. The detecting differentially regulated genes included those encoding virulence factors, antigenic proteins, ABC transporters and unknown functions. Our data provided a global profile of gene transcription induced by temperature alteration and shed light on some unforeseen lines for further pathogenesis investigation. A cDNA microarray imprinted with 2156 genes representing about 98% of 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 were prepared as biological replicates for RNA isolation . Accordingly, for each time point, four dual-fluorescence-labeled cDNA probes were prepared to hybridize with four slides, respectively. 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.