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Comparative analysis of whole-genome sequences of Streptococcus suis
Wu Wei,Guohui Ding,Xiaojing Wang,Jingchun Sun,Kang Tu,Pei HAO,Chuan Wang,Zhiwei Cao,Tieliu Shi,Yixue Li
Chinese Science Bulletin , 2006, DOI: 10.1007/s11434-006-1199-9
Abstract: The outbreak of Streptococcus suis recently in some districts of Sichuan Province in China has caused over 30 deaths and over 200 infections in human beings. In order to study the pathogenicity mechanism and to prevent the bacteria from spreading and infecting human beings and swine, we have annotated and analyzed the genomes of two strains, Streptococcus suis P1/7 and 89-1591 respectively. The whole length of P1/7 is 2.007 Mb, and has 1969 ORFs. In contrast, the partial genome sequence of 89-1591 is 1.98 Mb in length and exists in 177 contigs with 1918 ORFs. Analysis shows that the average lengths of CDSs in two genomes are very close, and the numbers of the homolog ORFs are 1306 between those two strains. Most of the toxicity factors of the two strains are homologeous, but there are still some significant differences between those two strains. For example, among the 11 genes (cps2A-cps2K) encoding for the capsules in P1/7, 4 (cps2A, 2B, 2I, 2J) are not detected in strain 89-1591. At the same time, the genes encoding EF and Haemolysin in P1/7 are also not found in strain 89-1591. Besides, the genes related to DNA replication, repair and recombination differ from each other significantly and there also exist certain differences among the surface proteins. Those characteristics indicate that those two strains have evolved their own specific functions to adapt to the different environments and that the pathogenesis of the two strains is different. We have accumulated comprehensive genomics information for future systematic studies of S. sui. Our results are helpful for disease prevention, vaccine development, as well as drug design for S. suis.
Comparative analysis of whole-genome sequences of Streptococcus suis
WEI Wu,DING Guohui,WANG Xiaojing,SUN Jingchun,TU Kang,HAO Pei,WANG Chuan,CAO Zhiwei,SHI Tieliu,LI Yixue,
WEI
,Wu,DING,Guohui,WANG,Xiaojing,SUN,dingchun,TU,Kang,HAO,Pei,WANG,Chuan,CAO,Zhiwei,SHI,Tieliu,LI,Yixue

科学通报(英文版) , 2006,
Abstract: The outbreak of Streptococcus suis recently in some districts of Sichuan Province in China has caused over 30 deaths and over 200 infections in human beings. In order to study the pathogenicity mechanism and to prevent the bacteria from spreading and infecting human beings and swine, we have annotated and analyzed the genomes of two strains, Streptococcus suis P1/7 and 89-1591 respectively. The whole length of P1/7 is 2.007 Mb, and has 1969 ORFs. In contrast, the partial genome sequence of 89-1591 is 1.98 Mb in length and exists in 177 contigs with 1918 ORFs. Analysis shows that the average lengths of CDSs in two genomes are very close, and the numbers of the homolog ORFs are 1306 between those two strains. Most of the toxicity factors of the two strains are homologeous, but there are still some significant differences between those two strains. For example, among the 11 genes (cps2A-cps2K) encoding for the capsules in P1/7, 4 (cps2A, 2B, 2I, 2J) are not detected in strain 89-1591. At the same time, the genes encoding EF and Haemolysin in P1/7 are also not found in strain 89-1591. Besides, the genes related to DNA replication, repair and recombination differ from each other significantly and there also exist certain differences among the surface proteins. Those characteristics indicate that those two strains have evolved their own specific functions to adapt to the different environments and that the pathogenesis of the two strains is different. We have accumulated comprehensive genomics information for future systematic studies of S. sui. Our results are helpful for disease prevention, vaccine development, as well as drug design for S. suis. These authors contributed equally to this work.
Identification of Genes and Genomic Islands Correlated with High Pathogenicity in Streptococcus suis Using Whole Genome Tilling Microarrays  [PDF]
Xiao Zheng,Han Zheng,Ruiting Lan,Changyun Ye,Yiting Wang,Ji Zhang,Huaiqi Jing,Chen Chen,Mariela Segura,Marcelo Gottschalk,Jianguo Xu
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0017987
Abstract: Streptococcus suis is an important zoonotic pathogen that can cause meningitis and sepsis in both pigs and humans. Infections in humans have been sporadic worldwide but two severe outbreaks occurred in China in recent years, while infections in pigs are a major problem in the swine industry. Some S. suis strains are more pathogenic than others with 2 sequence types (ST), ST1 and ST7, being well recognized as highly pathogenic. We analyzed 31 isolates from 23 serotypes and 25 STs by NimbleGen tiling microarray using the genome of a high pathogenicity (HP) ST1 strain, GZ1, as reference and a new algorithm to detect gene content difference. The number of genes absent in a strain ranged from 49 to 225 with a total of 632 genes absent in at least one strain, while 1346 genes were found to be invariably present in all strains as the core genome of S. suis, accounting for 68% of the GZ1 genome. The majority of genes are located in chromosomal blocks with two or more contiguous genes. Sixty two blocks are absent in two or more strains and defined as regions of difference (RDs), among which 26 are putative genomic islands (GIs). Clustering and statistical analyses revealed that 8 RDs including 6 putative GIs and 21 genes within these RDs are significantly associated with HP. Three RDs encode known virulence related factors including the extracellular factor, the capsular polysaccharide and a SrtF pilus. The strains were divided into 5 groups based on population genetic analysis of multilocus sequence typing data and the distribution of the RDs among the groups revealed gain and loss of RDs in different groups. Our study elucidated the gene content diversity of S. suis and identified genes that potentially promote HP.
Rapid Evolution of Virulence and Drug Resistance in the Emerging Zoonotic Pathogen Streptococcus suis  [PDF]
Matthew T. G. Holden, Heidi Hauser, Mandy Sanders, Thi Hoa Ngo, Inna Cherevach, Ann Cronin, Ian Goodhead, Karen Mungall, Michael A. Quail, Claire Price, Ester Rabbinowitsch, Sarah Sharp, Nicholas J. Croucher, Tran Bich Chieu, Nguyen Thi Hoang Mai, To Song Diep, Nguyen Tran Chinh, Michael Kehoe, James A. Leigh, Philip N. Ward, Christopher G. Dowson, Adrian M. Whatmore, Neil Chanter, Pernille Iversen, Marcelo Gottschalk, Josh D. Slater, Hilde E. Smith, Brian G. Spratt, Jianguo Xu, Changyun Ye, Stephen Bentley, Barclay G. Barrell, Constance Schultsz, Duncan J. Maskell, Julian Parkhill
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0006072
Abstract: Background Streptococcus suis is a zoonotic pathogen that infects pigs and can occasionally cause serious infections in humans. S. suis infections occur sporadically in human Europe and North America, but a recent major outbreak has been described in China with high levels of mortality. The mechanisms of S. suis pathogenesis in humans and pigs are poorly understood. Methodology/Principal Findings The sequencing of whole genomes of S. suis isolates provides opportunities to investigate the genetic basis of infection. Here we describe whole genome sequences of three S. suis strains from the same lineage: one from European pigs, and two from human cases from China and Vietnam. Comparative genomic analysis was used to investigate the variability of these strains. S. suis is phylogenetically distinct from other Streptococcus species for which genome sequences are currently available. Accordingly, ~40% of the ~2 Mb genome is unique in comparison to other Streptococcus species. Finer genomic comparisons within the species showed a high level of sequence conservation; virtually all of the genome is common to the S. suis strains. The only exceptions are three ~90 kb regions, present in the two isolates from humans, composed of integrative conjugative elements and transposons. Carried in these regions are coding sequences associated with drug resistance. In addition, small-scale sequence variation has generated pseudogenes in putative virulence and colonization factors. Conclusions/Significance The genomic inventories of genetically related S. suis strains, isolated from distinct hosts and diseases, exhibit high levels of conservation. However, the genomes provide evidence that horizontal gene transfer has contributed to the evolution of drug resistance.
Genetic diversity of Streptococcus suis isolates as determined by comparative genome hybridization
Astrid de Greeff, Henk J Wisselink, Freddy M de Bree, Constance Schultsz, Christoph G Baums, Hoa Thi, Norbert Stockhofe-Zurwieden, Hilde E Smith
BMC Microbiology , 2011, DOI: 10.1186/1471-2180-11-161
Abstract: In this study, the correlation between gene content, serotype, phenotype and virulence among 55 S. suis strains was studied using Comparative Genome Hybridization (CGH). Clustering of CGH data divided S. suis isolates into two clusters, A and B. Cluster A isolates could be discriminated from cluster B isolates based on the protein expression of extracellular factor (EF). Cluster A contained serotype 1 and 2 isolates that were correlated with virulence. Cluster B mainly contained serotype 7 and 9 isolates. Genetic similarity was observed between serotype 7 and serotype 2 isolates that do not express muramidase released protein (MRP) and EF (MRP-EF-), suggesting these isolates originated from a common founder. Profiles of 25 putative virulence-associated genes of S. suis were determined among the 55 isolates. Presence of all 25 genes was shown for cluster A isolates, whereas cluster B isolates lacked one or more putative virulence genes. Divergence of S. suis isolates was further studied based on the presence of 39 regions of difference. Conservation of genes was evaluated by the definition of a core genome that contained 78% of all ORFs in P1/7.In conclusion, we show that CGH is a valuable method to study distribution of genes or gene clusters among isolates in detail, yielding information on genetic similarity, and virulence traits of S. suis isolates.Streptococcus suis forms a problem in the swine industry. Clinically healthy sows carry S. suis in their nasal cavities and on their tonsils, and transmit the bacteria to their piglets [1], that develop a variety of infections, such as septicaemia, meningitis, polyarthritis, and endocarditis, and often do not survive [2]. S. suis occasionally causes meningitis, arthritis or endocarditis in humans. However, recently several large human outbreaks of S. suis have been described in China [3,4], and Thailand [5], whilst S. suis meningitis has become endemic in Vietnam [6,7], suggesting that isolates that are more virulent t
Prediction of an Essential Gene with Potential Drug Target Property in Streptococcus suis using comparative genomics
Aubhishek Zaman
Interdisciplinary Bio Central , 2012,
Abstract: Genes that are indispensible for survival are referred to as essential gene. Due to the momentous significance of these genes for cellular activity they can be selected potentially as drug targets. Here in this study, an essential gene for Streptococcus suis was predicted using coherent statistical analysis and powerful genome comparison computational method. At first the whole genome protein scatter plot was generated and subsequently, on the basis of statistical significance, a reference genome was chosen. The parameters set forth for selecting the reference genome was- the genome of the query (Streptococcus suis) and subject must fall in the same genus and yet they must vary to a good degree. Streptococcus pneumoniae was found to be suitable as the reference genome. A whole genome comparison was performed for the reference (Streptococcus pneumoniae) and the query genome (Streptococcus suis) and 14 conserved proteins from them were subjected to a screen for potential essential gene property. Among those 14 only one essential gene was found to be with impressive similarity score between reference and query. The essential gene encodes for a type of ‘Clp protease’. Clp proteases play major roles in degrading misfolded proteins. Results found here should help formulating a drug against Strptococcus suis which is responsible for mild to severe clinical conditions in human. However, like many other computational studies, the study has to be validated furthermore through in vitro assays for concrete proof.
A Glimpse of Streptococcal Toxic Shock Syndrome from Comparative Genomics of S. suis 2 Chinese Isolates  [PDF]
Chen Chen, Jiaqi Tang, Wei Dong, Changjun Wang, Youjun Feng, Jing Wang, Feng Zheng, Xiuzhen Pan, Di Liu, Ming Li, Yajun Song, Xinxing Zhu, Haibo Sun, Tao Feng, Zhaobiao Guo, Aiping Ju, Junchao Ge, Yaqing Dong, Wen Sun, Yongqiang Jiang, Jun Wang, Jinghua Yan, Huanming Yang, Xiaoning Wang, George F. Gao, Ruifu Yang, Jian Wang, Jun Yu
PLOS ONE , 2007, DOI: 10.1371/journal.pone.0000315
Abstract: Background Streptococcus suis serotype 2 (SS2) is an important zoonotic pathogen, causing more than 200 cases of severe human infection worldwide, with the hallmarks of meningitis, septicemia, arthritis, etc. Very recently, SS2 has been recognized as an etiological agent for streptococcal toxic shock syndrome (STSS), which was originally associated with Streptococcus pyogenes (GAS) in Streptococci. However, the molecular mechanisms underlying STSS are poorly understood. Methods and Findings To elucidate the genetic determinants of STSS caused by SS2, whole genome sequencing of 3 different Chinese SS2 strains was undertaken. Comparative genomics accompanied by several lines of experiments, including experimental animal infection, PCR assay, and expression analysis, were utilized to further dissect a candidate pathogenicity island (PAI). Here we show, for the first time, a novel molecular insight into Chinese isolates of highly invasive SS2, which caused two large-scale human STSS outbreaks in China. A candidate PAI of ~89 kb in length, which is designated 89K and specific for Chinese SS2 virulent isolates, was investigated at the genomic level. It shares the universal properties of PAIs such as distinct GC content, consistent with its pivotal role in STSS and high virulence. Conclusions To our knowledge, this is the first PAI candidate from S. suis worldwide. Our finding thus sheds light on STSS triggered by SS2 at the genomic level, facilitates further understanding of its pathogenesis and points to directions of development on some effective strategies to combat highly pathogenic SS2 infections.
Lysozyme Resistance in Streptococcus suis Is Highly Variable and Multifactorial  [PDF]
Paul J. Wichgers Schreur, Christian van Weeghel, Johanna M. J. Rebel, Mari A. Smits, Jos P. M. van Putten, Hilde E. Smith
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0036281
Abstract: Background Streptococcus suis is an important infectious agent for pigs and occasionally for humans. The host innate immune system plays a key role in preventing and eliminating S. suis infections. One important constituent of the innate immune system is the protein lysozyme, which is present in a variety of body fluids and immune cells. Lysozyme acts as a peptidoglycan degrading enzyme causing bacterial lysis. Several pathogens have developed mechanisms to evade lysozyme-mediated killing. In the present study we compared the lysozyme sensitivity of various S. suis isolates and investigated the molecular basis of lysozyme resistance for this pathogen. Results The lysozyme minimal inhibitory concentrations of a wide panel of S. suis isolates varied between 0.3 to 10 mg/ml. By inactivating the oatA gene in a serotype 2 and a serotype 9 strain, we showed that OatA-mediated peptidoglycan modification partly contributes to lysozyme resistance. Furthermore, inactivation of the murMN operon provided evidence that additional peptidoglycan crosslinking is not involved in lysozyme resistance in S. suis. Besides a targeted approach, we also used an unbiased approach for identifying factors involved in lysozyme resistance. Based on whole genome comparisons of a lysozyme sensitive strain and selected lysozyme resistant derivatives, we detected several single nucleotide polymorphisms (SNPs) that were correlated with the lysozyme resistance trait. Two SNPs caused defects in protein expression of an autolysin and a capsule sugar transferase. Analysis of specific isogenic mutants, confirmed the involvement of autolysin activity and capsule structures in lysozyme resistance of S. suis. Conclusions This study shows that lysozyme resistance levels are highly variable among S. suis isolates and serotypes. Furthermore, the results show that lysozyme resistance in S. suis can involve different mechanisms including OatA-mediated peptidolycan modification, autolysin activity and capsule production.
Development of Multiplex PCR Assays for the Identification of the 33 Serotypes of Streptococcus suis  [PDF]
Zhijie Liu, Han Zheng, Marcelo Gottschalk, Xuemei Bai, Ruiting Lan, Shaobo Ji, Haican Liu, Jianguo Xu
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072070
Abstract: Streptococcus suis is an important zoonotic agent causing severe diseases in pigs and humans. To date, 33 serotypes of S. suis have been identified based on antigenic differences in the capsular polysaccharide. The capsular polysaccharide synthesis (cps) locus encodes proteins/enzymes that are responsible for capsular production and variation in the capsule structures are the basis of S. suis serotyping. Multiplex and/or simplex PCR assays have been developed for 15 serotypes based on serotype-specific genes in the cps gene cluster. In this study, we developed a set of multiplex PCR (mPCR) assays to identify the 33 currently known S. suis serotypes. To identify serotype-specific genes for mPCR, the entire genomes of reference strains for the 33 serotypes were sequenced using whole genome high-throughput sequencing, and the cps gene clusters from these strains were identified and compared. We developed a set of 4 mPCR assays based on the polysaccharide polymerase gene wzy, one of the serotype-specific genes. The assays can identify all serotypes except for two pairs of serotypes: 1 and 14, and 2 and 1/2, which have no serotype-specific genes between them. The first assay identifies 12 serotypes (serotypes 1 to 10, 1/2, and 14) that are the most frequently isolated from diseased pigs and patients; the second identifies 10 serotypes (serotypes 11 to 21 except 14); the third identifies the remaining 11 serotypes (serotypes 22 to 31, and 33); and the fourth identifies a new cps cluster of S. suis discovered in this study in 16 isolates that agglutinated with antisera for serotypes 29 and 21. The multiplex PCR assays developed in this study provide a rapid and specific method for molecular serotyping of S. suis.
Comparative genomic analysis of Streptococcus suis reveals significant genomic diversity among different serotypes
Anding Zhang, Ming Yang, Pan Hu, Jiayan Wu, Bo Chen, Yafeng Hua, Jun Yu, Huanchun Chen, Jingfa Xiao, Meilin Jin
BMC Genomics , 2011, DOI: 10.1186/1471-2164-12-523
Abstract: Four Chinese S. suis strains belonging to serotypes 1, 7, 9 and 1/2 were sequenced using a rapid, high-throughput approach. Based on the 13 corresponding serotype strains, including 9 previously completed genomes of this bacterium, a full comparative genomic analysis was performed. The results provide evidence that (i) the pan-genome of this species is open and the size increases with addition of new sequenced genomes, (ii) strains of serotypes 1, 3, 7 and 9 are phylogenetically distinct from serotype 2 strains, but all serotype 2 strains, plus the serotype 1/2 and 14 strains, are very closely related. (iii) all these strains, except for the serotype 1 strain, could harbor a recombinant site for a pathogenic island (89 K) mediated by conjugal transfer, and may have the ability to gain the 89 K sequence.There is significant genomic diversity among different strains in S. suis, and the gain and loss of large amount of genes are involved in shaping their genomes. This is indicated by (i) pairwise gene content comparisons between every pair of these strains, (ii) the open pan-genome of this species, (iii) the observed indels, invertions and rearrangements in the collinearity analysis. Phylogenetic relationships may be associated with serotype, as serotype 2 strains are closely related and distinct from other serotypes like 1, 3, 7 and 9, but more strains need to be sequenced to confirm this.Streptococcus suis (S. suis) is a major swine pathogen responsible for severe economic losses in the pork industry and is emerging as an important threat to human health, especially to people who have close contact with swine or pork by-products [1-3]. Since the first reported case of human meningitis caused by S. suis in Denmark in 1968, cases of infection have been reported continuously in more than 20 countries, with more than 700 people being affected [4]. Two recent large-scale outbreaks of human S. suis infections in China (one associated with 25 cases and 14 deaths in Jiangsu
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