title: Streptococcus iniae SF1: complete genome sequence, proteomic profile, and immunoprotective antigens.
abstract: Streptococcus iniae is a Gram-positive bacterium that is reckoned one of the most severe aquaculture pathogens. It has a broad host range among farmed marine and freshwater fish and can also cause zoonotic infection in humans. Here we report for the first time the complete genome sequence as well as the host factor-induced proteomic profile of a pathogenic S. iniae strain, SF1, a serotype I isolate from diseased fish. SF1 possesses a single chromosome of 2,149,844 base pairs, which contains 2,125 predicted protein coding sequences (CDS), 12 rRNA genes, and 45 tRNA genes. Among the protein-encoding CDS are genes involved in resource acquisition and utilization, signal sensing and transduction, carbohydrate metabolism, and defense against host immune response. Potential virulence genes include those encoding adhesins, autolysins, toxins, exoenzymes, and proteases. In addition, two putative prophages and a CRISPR-Cas system were found in the genome, the latter containing a CRISPR locus and four cas genes. Proteomic analysis detected 21 secreted proteins whose expressions were induced by host serum. Five of the serum-responsive proteins were subjected to immunoprotective analysis, which revealed that two of the proteins were highly protective against lethal S. iniae challenge when used as purified recombinant subunit vaccines. Taken together, these results provide an important molecular basis for future study of S. iniae in various aspects, in particular those related to pathogenesis and disease control.
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Graduate University of the Chinese Academy of Sciences, Beijing, China.
authors.forename: Bao-cun
authors.initials: BC
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Graduate University of the Chinese Academy of Sciences, Beijing, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Collaborative Innovation Center of Deep Sea Biology, Zhejiang University, Hangzhou, China.
authors.forename: Li
authors.initials: L
authors.lastname: Sun
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology*; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology; D001428:Bacterial Vaccines / Q000235:genetics / Q000276:immunology; D001483:Base Sequence; D001692:Biological Transport / Q000235:genetics; D064113:CRISPR-Cas Systems; D005110:Extracellular Space / Q000378:metabolism; D005412:Flatfishes / Q000276:immunology / Q000382:microbiology; D016680:Genome, Bacterial / Q000235:genetics*; D039002:Prophages / Q000502:physiology; D040901:Proteomics; D017421:Sequence Analysis; D044967:Serum / Q000276:immunology; D013291:Streptococcus / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism / Q000821:virology; D014614:Vaccines, Synthetic / Q000235:genetics / Q000276:immunology; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D014614:Vaccines, Synthetic; D037521:Virulence Factors