Abstract
Streptococcus suis is a major swine pathogen responsible for significant, worldwide economic losses in the swine industry, in addition to being an emerging zoonotic agent. Strains of serotype 2 are the most commonly associated with infections causing meningitis, endocarditis, and septicemia. Here we present the genome sequence of S. suis serotype 2 strain S735.
GENOME ANNOUNCEMENT
Streptococcus suis is a major swine pathogen worldwide, endemic in all countries where intensive pig farming is practiced, causing meningitis, endocarditis, arthritis, pneumonia, and septicemia (3, 8). S. suis is also considered an emerging zoonotic agent, especially in Asian countries (6, 7). The massive use of antibiotics for growth promotion or for prophylaxis and therapy in the swine industry may contribute to the emergence and spread of antibiotic resistance in S. suis (10). Strains of serotype 2 are mostly responsible for severe infections in both swine and humans (3, 8). King et al. (9) developed a multilocus sequence typing (MLST) scheme and showed that S. suis serotype 2 isolates can be classified into at least 16 sequence types (STs), the most invasive strains belonging to the sequence type 1 (ST1) complex. Recently, Fittipaldi et al. (4) performed MLST on North American S. suis serotype 2 porcine isolates and reported that most strains can be classified into three major classes: ST1 (high virulence, low prevalence in North America), ST25 (intermediate virulence), and ST28 (low virulence). Here we report the genome sequence of S. suis serotype 2 strain S735 (NCTC 10234), an ST1 European (The Netherlands) reference strain isolated from a case of pneumonia in a pig (2).
The total genomic DNA of S. suis S735 was extracted using the method of Stuart et al. (11). Whole-genome shotgun DNA sequencing of S. suis S735 was performed using the Roche 454 pyrosequencing method on the Genome Sequencer FLX+ system at the Plateforme d'analyses génomiques of the Institut de Biologie Intégrative et des Systèmes (IBIS, Université Laval). In total, 70,238,071 bases were analyzed using the gsAssembler module of Newbler v2.5.3. A total of 37 contigs were produced, all of them larger than 500 bases. Contigs were merged using Consed (5). Two regions could not be resolved by 454 sequencing, and primers were designed to PCR amplify and Sanger sequence these regions. The DNA isolated from S. suis S735 was assembled into a single 1,980,887-nucleotide circular genome. Multiple, complete genome alignments using Mauve (1) and several published S. suis genomes (accession numbers AM946016.1, CP000408.1, CP000837.1, FM252031.1, and FM252032.1) identified a potential large inversion site bounded by a 1,529-nucleotide inverted repeat element. The orientation of this region was verified by PCR to ensure proper assembly. The genome of S. suis S735 was found to be in the same orientation as the majority of the published genomes in GenBank, leaving a single genome with the inversion.
The genome of S. suis S735 is slightly smaller than other sequences from the same species (27 kb smaller than S. suis strain P1/7). Three elements absent in S. suis S735 (totaling 28 kb) compared to P1/7 were previously identified as genomic islands or putative phage-related genomic islands. These elements are not present in all sequenced strains to date and could be potential pathogenicity determinants.
Nucleotide sequence accession number.
The nucleotide sequence for the draft genome sequence of S. suis S735 has been deposited in DDBJ/EMBL/GenBank under the accession no. CP003736.
ACKNOWLEDGMENTS
This study was supported by grants from the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Centre de Recherche en Infectiologie Porcine (CRIP), Fonds de Recherche du Québec-Nature et Technologies (FRQNT). S.J.C. is a research scholar of the Fonds de Recherche du Québec-Santé (FRQS).
REFERENCES
- 1. Darling AE, Mau B, Perna NT. 2010. progressiveMauve: multiple genome alignment with gene gain, loss and rearrangement. PLoS One 5:e11147 doi:10.1371/journal.pone.0011147 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2. De Moor CE. 1963. Septicaemic infections in pigs caused by hemolytic streptococci of new Lancefield groups designated R, S, and T. Antonie Van Leeuwenhoek 29:272–280 [DOI] [PubMed] [Google Scholar]
- 3. Fittipaldi N, Segura M, Grenier D, Gottschalk M. 2012. Virulence factors involved in the pathogenesis of the infection caused by the swine pathogen and zoonotic agent Streptococcus suis. Future Microbiol. 7:259–279 [DOI] [PubMed] [Google Scholar]
- 4. Fittipaldi N, et al. 2011. Lineage and virulence of Streptococcus suis serotype 2 isolates from North America. Emerg. Infect. Dis. 17:2239–2244 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5. Gordon D, Abajian C, Green P. 1998. Consed: a graphical tool for sequence finishing. Genome Res. 8:195–202 [DOI] [PubMed] [Google Scholar]
- 6. Gottschalk M, et al. 2010. Streptococcus suis infections in humans: what is the prognosis for Western countries? (Part I). Clin. Microbiol. Newsl. 32:89–96 [Google Scholar]
- 7. Gottschalk M, et al. 2010. Streptococcus suis infections in humans: what is the prognosis for Western countries? (Part II). Clin. Microbiol. Newsl. 32:97–102 [Google Scholar]
- 8. Higgins R, Gottschalk M. 2005. Streptococcal diseases, p 769–783 In Straw BED', Allaire S, Mengeling WL, Taylor DJ. (ed), Diseases of swine, 9th ed. University of Iowa Press, Iowa City, IA [Google Scholar]
- 9. King SJ, et al. 2002. Development of a multilocus sequence typing scheme for the pig pathogen Streptococcus suis: identification of virulent clones and potential capsular serotype exchange. J. Clin. Microbiol. 40:3671–3680 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10. Palmieri C, Varaldo PE, Facinelli B. 2011. Streptococcus suis, an emerging drug-resistant animal and human pathogen. Front. Microbiol. 2:235. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11. Stuart JG, Zimmerer EJ, Maddux RL. 1992. Conjugation of antibiotic resistance in Streptococcus suis. Vet. Microbiol. 30:213–222 [DOI] [PubMed] [Google Scholar]