| Streptococcus suis serotype2(S.suis2) is an important zoonotic pathogen, its infection would cause a variety of diseases, such as meningitis, septicemia, arthritis streptococcal toxic shock syndrome and so on. So far, the interspecies transmission and pathogenesis of S.suis2is not clear, and the research of its virulence factors is not comprehensive. To further investigate the pathogenesis of S.suis2, in this research, we report three single nucleotide resolution transcriptom maps of S.suis2using strand-specific RNA-seq method, including the two Chinese highly pathogenic S.suis2(05ZYH33and98HAH33) that can infect human and foreign non-pathogenic strains S.suis2(PI/7) under the same growth conditions.Based on the analysis of high-throughput transcriptome data, a total of120dfferentially expressed genes were identified in three strains, including53up-regulated genes and66down-regulated genes in both of the pathogens. The former are enriched in translation, ribosomal structure, biosynthesis, including the most significant dfferentially expressed gene encoding surface-anchored protein. The latter are mainly enriched in phosphotransferase system (PTS), carbohydrate transport and metabolism, inorganic ion transport and metabolism, glycolysis/gluconeogenesis and tyrosine metabolism. These results show that the energy metabolism and sugar conversion changed between the pathogenic and non-pathogenic strains, suggesting that energy metabolism between them is different, and S.suis2pathogens prefer the growth environment of rich sugar and amino acid. There is also a gene up-regulated in05ZYH33but down-regulated in98HAH33, which may worth further research the function of the gene. In addition, the up-regulated genes in PTS and tyrosine metabolic pathway catalyze the synthesis of necessary substances for S.suis2growth, and a down-regulated gene in glycolysis/gluconeogenesis pathway catalyze the toxic acetaldehyde generation. Pathogens metabolic activity changes can affect their virulence, and it is very important content for the study of the pathogenesis of S.suis2.In the study of virulence factors, we first analyze the gene expression of89K pathogenicity, and found that the genes in a Toxin-antitoxin system (TAS) have higher expression and a Two-Component System(TCS) expressed, which is an important candidate in the further study of S.suis2virulence. Then by comparising with the virulence factor database, a total of96virulence factors in the three S.suis2strains were identified in the study. These virulence factors are mainly involved in adhesion, biofilm formation, the synthesis and transport of the outer membrane protein. The up-regulated virulence factors in both of the pathogens involved in the ABC transporter pathway, indicating that the virulence of S.suis2may be involved in the transport of iron and a variety of proteins. Moreover,8pathogen-specific virulence factors were identified, mainly including capsular polysaccharide, lipopolysaccharide and agglutinin receptor. Finally, using transcriptome data,we optimized the current genome annotation of S.suis2, finding that in both of the pathogens intergenic there is a new gene encoding a toxin and a new gene encoding antibiotic, and rli38sRNA, it is worth exploring their roles in virulence of S.suis2.In this study, based on RNA-seq data, we analyzed the transcriptome of S.suis2that grew under log phase, and initially completed the optimization of the current genome annotation. We found that:1) the virulence of S.suis2may be involved in some key bacteria metabolic pathway;2) identifying pathogen-specific expression of the virulence-related pathway and virulence factors are identified, and3) three new genes that may impact on the virulence of S.suis2are discovered. All of these observations provide an important insight into further study of the interspecies transmission and pathogenic mechanisms of S.suis2. |
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