Streptococcus suis is an important pathogen in swine, and it also represents an emerging zoonotic agent. Zebrafish as a model for the evaluation of virulence of S. suis has been demonstrated before. Here, an Affymetrix Zebrafish GeneChip was used to identify alterations in gene expression of zebrafish injected with S. suis serotype 2 strain HA9801. The results showed that 189 genes were differentially expressed, of which 125 genes were upregulated and 64 genes were downregulated. Gene Ontology category and KEGG pathway were analyzed for differentially expressed genes. Upregulated genes were involved in response to bacterium, immune response, inflammatory response, complement activation, defense response. Three genes (encoding serum amyloid protein A, matrix metalloproteinase 9 and apoptosis-related cysteine protease) and genes involved in the regulation of IL-6 biosynthetic process, which have previously been implicated in the response to S. suis infection in other organisms, were also upregulated. Downregulated genes played roles in glycolysis, carbohydrate metabolic process, amino acids metabolism, behavior and muscle. The reliability of the data obtained from the microarray was verified by performing quantitative real-time PCR on 12 representative genes. The data may provide further validation of this model, which will contribute to understanding of S. suis pathogenic mechanisms.
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