Homology analysis and historical tracing for inter-continental Burkholderia pseudomallei strains of sequence type 562 / 中华流行病学杂志

Objective To understand the homology of sequence type 562 (ST562) strains of Burkholderia pseudomallei which circulated in two separate continents (Asia and Australia) at different times.Methods Spe Ⅰ restriction fragments and 4-locus multiple locus variable number tandem repeat analysis (MLVA-4) profiles were extracted from MSHR5858 (ST562 Australia strain) and 350105 (ST562 historical strain of Hainan) genomes respectively by in silico analysis and then compared with the PFGE and MLVA-4 results of five ST562 clinical isolates from Hainan to test their homology.Synteny and homology between MSHR5858 and 350105 genomes were evaluated with bioinformatics methods.Results Five ST562 clinical strains from Hainan shared same PFGE pattern (similarity ＞97％) and this pattern coincided to the map of Spe Ⅰ restriction fragments of Australian strain MSHR5858.The amounts of genomic restriction fragments (Spe Ⅰ) for MSHR5858 and 350105 were 31 and 34 respectively,with 31 of them matched by each other.Five ST562 clinical strains of Hainan were distinct by MLVA-4 profiles,among which HPPH43 (MLVA-4 profile:10,8,10,8) was close to Australia strain MSHR5858 (10,8,8,6),containing identical repeat numbers at VNTR loci 2341k and 1788k;while HK003 (11,8,15,7) and HK061 (11,8,17,7) similar to Hainan historical strain 350105 (11,8,11,8),with same repeat numbers at loci 2341k and 1788k also.High-degree synteny and consistency on genomic contents were observed between 350105 and MSHR5858,indicating a similar origin for the 2 strains.Conclusion All inter-continental and historical ST562 strains ofB.pseudomallei had similar genomic characteristics,supporting the assumption that they had a common origin.Also,it is possible that Hainan historical strain 350105 is the ancestor of all circulating ST562 strains.

Homology analysis and historical tracing for inter-continental Burkholderia pseudomallei strains of sequence type 562 / 中华流行病学杂志

Objective To understand the homology of sequence type 562 (ST562) strains of Burkholderia pseudomallei which circulated in two separate continents (Asia and Australia) at different times.Methods Spe Ⅰ restriction fragments and 4-locus multiple locus variable number tandem repeat analysis (MLVA-4) profiles were extracted from MSHR5858 (ST562 Australia strain) and 350105 (ST562 historical strain of Hainan) genomes respectively by in silico analysis and then compared with the PFGE and MLVA-4 results of five ST562 clinical isolates from Hainan to test their homology.Synteny and homology between MSHR5858 and 350105 genomes were evaluated with bioinformatics methods.Results Five ST562 clinical strains from Hainan shared same PFGE pattern (similarity ＞97％) and this pattern coincided to the map of Spe Ⅰ restriction fragments of Australian strain MSHR5858.The amounts of genomic restriction fragments (Spe Ⅰ) for MSHR5858 and 350105 were 31 and 34 respectively,with 31 of them matched by each other.Five ST562 clinical strains of Hainan were distinct by MLVA-4 profiles,among which HPPH43 (MLVA-4 profile:10,8,10,8) was close to Australia strain MSHR5858 (10,8,8,6),containing identical repeat numbers at VNTR loci 2341k and 1788k;while HK003 (11,8,15,7) and HK061 (11,8,17,7) similar to Hainan historical strain 350105 (11,8,11,8),with same repeat numbers at loci 2341k and 1788k also.High-degree synteny and consistency on genomic contents were observed between 350105 and MSHR5858,indicating a similar origin for the 2 strains.Conclusion All inter-continental and historical ST562 strains ofB.pseudomallei had similar genomic characteristics,supporting the assumption that they had a common origin.Also,it is possible that Hainan historical strain 350105 is the ancestor of all circulating ST562 strains.

Genetic diversity of Francisella tularensis subsp.holarctica in China / 中华流行病学杂志

Objective To explore the genetic relationship between the Chinese and the foreign species of Francisella tularensis.Methods Based on our own findings and from the literature,17 SNP,4 INDEL,and 12 VNTR were selected for phylogenetic analysis on 39 strains of F.tularensis,including 10 strains of Chinese F.tularensis and 29 strains of foreign F.tularensis that had been sequenced and published.SNP-INDEL and MLVA were used for the separation and combination.Results Data from the combined analysis indicated that 3 strains of Chinese F.tularensis with Japanese FSC022 were assigned to B5;3 strains,with Swedish FSC200 to B1;3 strains with American OSU18 to B2 and 1 strain with French FTNF002-00,German F92,and American OR96246 to B4,respectively.10 strains of Chinese F.tularensis were assigned to 4 clades and the result demonstrated a wide diversity of F.tularensis subsp.holarctica in China.Conclusion A set of simple and robust typing tools for F.tularensis subsp.holarctica were established in this study.Based on the results,F.tularensis subsp.holarctica might have had its origins in Asia.

Discovery and tracking source of the new subgroup of Chinese Francisella tularensis type B / 中华预防医学杂志

<p><b>OBJECTIVE</b>To perform laboratory diagnosis and tracking source of a suspected tularemia patient in Beijing.</p><p><b>METHODS</b>A suspected tularemia patient was reported in Beijing city on July 19, 2012. Genomic DNA was extracted from the blood sample of the patient, then general PCR and sequencing of amplicons were conducted using 3 specific genes (fopA, tul4 and 16S rRNA) Francisella tularensis (F.tularensis), and 2 genotyping primers (C1C4 and RD1). Two other laboratories repeated the PCR and sequencing of the fopA in parallel. At the same time, real-time PCR fluorescent ration was performed using 4 targets (fopA, ISFtul2, 23kDa, and tul4), and phylogenetic analysis was carried out using 11 canonical single nucleotide polymorphisms (SNPs) and 4 insertions or deletions.</p><p><b>RESULTS</b>All the 3 specific genes were amplified positively, and sequenced fragments were 409, 407 and 1 053 bp, respectively. The patient was infected by F. tularensis comparing with the whole genome published. Next, amplicons of 151 and 924 bp were obtained by the 2 typing primers after sequencing, respectively. The segment lengths suggested that the patient was infected by the subsp. holarctica. All of the two other laboratories obtained positive data for the PCR and sequencing of the fopA. In addition, all the 4 targets tested positive by real-time PCR for F. tularensis. The Ct value of the fopA, ISFtul2, 23kDa and tul4 were 30, 25, 28, and 30, respectively. The phylogenetic analysis indicated that the whole genome of this case was assigned to a known clade from Russia, which was subgroup B3.</p><p><b>CONCLUSION</b>This case was confirmed to be a tularemia patient, and a new subgroup of F. tularensis type B was found in China.</p>

Establishment and evaluation of identification method for Yersinia pestis and Yersinia pseudotuberculosis / 中华流行病学杂志

<p><b>OBJECTIVE</b>To establish a gene identification method of Yersinia pestis and Yersinia pseudotuberculosis for plague surveillance.</p><p><b>METHODS</b>According to the specific genomic sequences of Y. pestis and Y. pseudotuberculosis, i.e. "pestis Island (PeI)" and "pseudotuberculosis Island (PsI)" and the published genomic sequences of 12 strains of Y. pestis and 4 strains of Y. pseudotuberculosis, the specific identification primers of these sequences were designed.</p><p><b>RESULTS</b>A total of 52 strains of Y. pestis and 57 strains of Y. pseudotuberculosis and other intestinal bacteria strains were tested with PCR. Of the 5 pairs of Y. pestis identification primers, PeI2 and PeI11 were specific for Y. pestis. Besides Y. pestis, the primers PeI1, PeI3 and PeI12 could detect part of 57 Y. pseudotuberculosis strains. Of the 5 pairs of Y. pseudotuberculosis identification primers, PsI1 could detect all the 52 strains of Y. pestis and 57 strains of Y. pseudotuberculosis. PsI7, PsI16, PsI18 and PsI19 were specific for Y. pseudotuberculosis.</p><p><b>CONCLUSION</b>The primers PsI1, PeI 2 and PeI11, PsI7, PsI16, PsI18 and PsI19 can be used in the rapid identification of Y. pestis and Y. pseudotuberculosis, which can be also used to explore the circulation of atypical Y. pestis in quiescent plague foci.</p>

Chromosomal structural features of Yersinia pestis isolated from China / 中华地方病学杂志

Objective To study the differences of chromosomal structure among Yersinia pestis strains isolated from China,and to investigate the reasons of chromosomal rearrangement events occurred in Yersinia pestis as well as the possibility of strain identification and phylogenetic analysis based on the chromosomal rearrangement features.Methods According to the genome sequence data downloaded from web of National Center for Biotechnology Information (http://www.ncbi.nlm.nih.gov/genome),alignment of all the coding sequences (CDSs) among five strains(American strain CO92 as reference and other four completely sequenced strains from Inner Mongolia,Jianchuan of Yunnan,Yulong of Yunnan,Naqu of Tibet in China named 91001,D182038,D106004 and Z176003 as comparison strains) was performed,and then the chromosome of Yersinia pestis was divided into several large DNA segments (named chromosomal plate in the text) according to the similarity of CDSs.Plate arrangement patterns in each strain' s chromosome and gene content of breakpoint regions were determined.Finally,genetic relationships among Yersinia pestis strains were analyzed on the basis of rearrangement diversity from paired-comparison.Results Yersinia pestis chromosomes of strains CO92,D182038,D106004,91001 were composed of 44 relatively independent plates,except strain Z176003.Gene order was very stable within each plate,while it was movable between the plates.Comparing with the reference strain CO92,13 rearrangement events occurred in the chromosomes of both strain D182038 and strain D106004,and 14 rearrangement events involved in Z176003,while 37 rearrangement events occurred in 91001.Paired-comparison data showed that only 8 plates order differences were existed between D106004 and Z176003.Forty-three breakpoint regions were identified on the chromosome of strain CO92,and 39 of them contained insertion sequences,and 25 of them were IS100.Conclusions Yersinia pestis genome represents a high degree of genetic flux,and chromosomal structures of strains are significantly different from each other.Chromosomal rearrangement events is closely related to the large number of insertion sequences in the Yersinia pestis chromosome.Rearrangement diversity among Yersinia pestis strains could reflect their genetic relationships.

Study on the spatial and temporal distribution of animal plague in Junggar Basin plague focus / 中华流行病学杂志

<p><b>OBJECTIVE</b>To explore the spatial and temporal distributions of animal plague in Junggar Basin natural plague focus.</p><p><b>METHODS</b>Data regarding plague antibody (F1) in serum of Great Gerbil (Rhombomys opimus, R. opimus) which were collected from 2005 to 2012 in Junggar Basin and analyzed. The changing rates on the positivity of F1 that appeared spatially and temporally were also analyzed.</p><p><b>RESULTS</b>A total of 4 825 R. opimus serum samples were collected in 13 administrative regions in Junggar Basin.</p><p><b>RESULTS</b>showed that plague R. opimus existed in two areas-Gurbantonggut desert in the eastern-center and the clay desert of western Junggar Basin. However, in these two areas, the intensity of animal plague prevalence was different. In the former region where Yesinia pestis positive serum was detected from R. opimus, the detected rate of R. opimus was 8.39%. However, in the latter areas, the average positive rate was 1.56%. The changing trends of R. opimus plague prevalence were also varied annually. In the western Junggar Basin, the trend showed a slowly downward profile. The serum positive rate of R. opimus for Yesinia pestis decreased, from 7.59% in 2005 to 0.61% in 2008, and appeared as a resting state that none of the positive sample could be found since then. However, in the eastern-center Junggar Basin area-also named as Gurbantonggut desert which had been divided into 3 segments(western, central and eastern, according to related geographical characteristics), the changing trends of animal plague seemed quite complex. In the western segment, the animal plague had two epidemic peaks-in 2006 and 2010, with the interval of 4 years, with the higher peak of all the three geographic segments as 45.65% in 2010 and the positive serum of R. opimus for plague could be detected each year from 2006 to 2012. However, there were 3 epidemic peaks in the same period in the central and eastern segments. In the central segment, the peaks appeared in 2006, 2009 and 2011, with the intervals as 2.5 years and the average positive rate 8.92% was seen the lowest in Gurbantonggut desert. In the eastern segment, the first 2 peaks appeared the same season as in the central segment, but the third peak appeared in 2012, with the peak interval as 3 years. The positive rate of R. opimus for plague was also different in seasons, with the positive rate higher in autumn than in spring. These findings showed that the animal plague could be continuously prevalent from spring to autumn in the natural foci of plague in the Junggar Basin.</p><p><b>CONCLUSION</b>Both geographical and temporal fluctuations of animal plague existed in the natural foci of Junggar Basin which was also named as geographical heterogeneity. Consequently, animal plague could be divided into two areas-the clay plains desert in the western and the Gurbantonggut desert in the eastern-center Junggar Basin.</p>

Genetic relationship between Francisella tularensis strains from China and from other countries / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To study the types of subspecies of Francisella tularensis from China and to investigate the genetic relationships between F. tularensis strains from China and from other countries.</p><p><b>METHODS</b>Ten strains of F. tularensis isolated from China were amplified by using typing primers C1/C4 and RD1. On the basis of the lengths of the polymerase chain reaction (PCR) products, it was concluded that these strains of F. tularensis belonged to the same subspecies. At the same time, the fopA, tul4, and 16S rRNA genes of the 10 strains were amplified, and a three-gene based phylogenetic analysis was performed using the Molecular Evolutionary Genetics Analysis software version 4.0.</p><p><b>RESULTS</b>The 10 strains of F. tularensis from China were all identified as belonging to subspecies holarctica (type B). We found no direct relationship between the genotypes of F. tularensis subsp. holarctica and the geographical area from where they were isolated.</p><p><b>CONCLUSION</b>The F. tularensis strains isolated from North China mainly belong to subspecies holarctica (type B). The strains of F. tularensis subsp. holarctica from China may have evolved earlier than those from Europe and North America.</p>