Comparative genomic analysis of gene variations of two Chinese Yersinia pestis isolates from vaccine strain EV76 / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To investigate genomic variations of two Chinese Yersinia pestis isolates that were isolated from different plague foci obtained from vaccine strain EV76 from the Yunnan province of China.</p><p><b>METHODS</b>A microarray containing 12 000 probes covering the entire genome of seven Yersinia pestis and two Yersinia pseudotuberculosis strains, was used. PCR assays were performed to confirm microarray results.</p><p><b>RESULTS</b>The gene variations detected included the absence of five genes related to the synthesis of betaine in both EV76 and another sequenced attenuated strain, KIM D27. Several genes related to phage-related membrane proteins were found to be absent in the Antiqua biovar Yunnan strain, 485, which was isolated from a rodent plague foci.</p><p><b>CONCLUSION</b>These findings provide initial insight into the distinct strains isolated from natural foci, within their genomic context, including Yunnan Y. pestis strains. This information will be used therefore to establish subsequent comparisons of these sequences with published complete genomes of other strains.</p>

Single nucleotide polymorphisms characteristics of the Yersinia Pestis in China / 中国地方病学杂志

Objective To study the single nucleotide polymorphisms (SNP) characteristics of Yersinia pestis strains from different natural foci in China.Methods Genome-wide comparison was done to find SNP sites by the Mummer program among 9 Yersinia pestis genome which was downloaded from NCBI.Then 13 genic fragments including 19 SNP sites were amplified by PCR and sequenced in 133 Yersinia pestis strains,and the results were cluster analyzed with the BioNumerics software.Results Three thousand seven hundred and eighty sequence variation sites were found by genome-wide comparison.Using the different combinations of SNP sites,UPGMA cluster analysis revealed obvious geographic regional and eco-aggregation characteristics of Yersinia pestis strains isolated from China.Conclusions As relatively stable genetic markers,SNP can better reflect the genome characteristics of Yersinia pestis in different plague natural foci of China.

Study on the identification characteristics of rRNA genes on Yersinia pestis / 中华流行病学杂志

Objective To study the identification characteristics of rRNA genes on Yersinia (Y.)pestis.Methods By means of comparative genomics,we compared the rRNA genome sequences of nine completely sequenced strains of Y. pestis isolated from China and other countries by Clustal W software.we also compared the 2000 bp sequence adjacent to the rRNA genes,rRNA genes and 16S-23S rRNA spacer region respectively to determine the identification features of rRNA genes for Y. pestis.Results There were 6 rRNA gene clusters in the strains of D182038,D106004,Z176003 and CO92 respectively(6 copies strain).There were 7 rRNA gene clusters in the strains of 91001,KIM,Nepa1516,Antiqua and Pestoides F(7 copies strain).According to the 2000 bp sequence,13 types of rRNA gene clusters could classify the strains between the 6 copies and 7 copies.There were 4 types of tRNA gene among the 16S-23S rRNA spacer region that could classify the strains among the 6 copies and 7 copies strains respectively.The number of point mutation among the 23S rRNA gene was statistically different in some copies under ANOVA analysis(F=0.548,P=0.815>0.05 among the strains and F=5.228,P<0.01 among the copies).Conclusion The 2000 bp sequence adjacent to the rRNA genes,tRNA gene and 23S rRNA gene sequence could serve as the identification sign of rRNA genes for classifing the strains of Y. pestis.

Comparison of Yersinia pestis genomes from a new natural foci in China / 中国地方病学杂志

Objective Measurement and analysis of the complete genome sequences of Yersinia Pestis from a new plague natural foci and adjacent foci in China, to know the genetic relationship among the epidemic strain isolated in Yulong (D 106004) and Jianchuan strains (D 182038) and the Tibetan strain ( Z 176003 ). Methods Three complete genome sequences were sequenced using the whole-genome shotgun and Solexa method and comparative genomics analysis was done among the three sequences. Genome comparative analysis among the coding sequences was done by BLAST software, SNPs finding was done by the program, genome rearrangements were analyzed using MAUVE software. Results All of the genomes of Yersinia pestis strains D182038, D106004 and Z176003 consist of a single circular chromosome and three virulence plasmids, pMT1, pCD1 and pPCP1. They had similar characteristics in chromosome and plasmid features, and there were no significant difference in coming sequence (CDS) of the cluster of orthologous groups of proteins (COG) functional classification and the number of insertion sequence in the three strains (x2 =3.03, 0.257, all P ＞ 0.05). The comparative genomics results showed that the three bacteria had 2882 genes with 100％ homology, of 3636 genes predicted in D106004, 2994 were identical with D182038's and 3113 with Z176003's, and of which 240 had 90％ homology with D182038's and 200 with Z176003 's. Synonymous single nucleotide polymorphisms(sSNPs) were 59 and 68, and non-synonymous SNPs(nsSNPs) were 104 and 203 between strains D106004 and Z176003/D182038. There were 11 segments rearrangements between D106004 and Z176003, which was less than 16 segments rearrangements between D106004 and D182038. ConclusionsThe three strains are highly homologous, the Yulong strain has more similarity with Tibet strain than with Jianchuan strain, the strain from Yulong foci may be evolved from Tibet foci.

Clone expression of the caf1 gene of Yersinia pestis and immunological evaluation on recombinant F1 antigen / 中华流行病学杂志

Objective To get recombinant F1 antigen (rF1) and to construct the detection dipstick of plague antibody. Methods The cafl gene removing the signal peptide coding sequence was cloned into plasmid pET32a ( +) by double-digested sites of BamHI and Not I. Recombinant plasmid caf1-pET32a(+) was transformed into BL21 (DE3) and the rFl was expressed. Expression products were purified by affinity chromatography. Dual detection dipstick of plague antibody was constructed with purified rF1 and natural F1, and evaluated with 528 human serum samples of Zhejiang province. Results The fusion protein rF1 of 35.5 KD was expressed by BL21 strains containing caf1-pET32a( + ). The sensitivity of rF1 showed equivalent to or higher than the natural Fl antigen in detecting plague antibody. It seemed that there was a better consistency of 97.9% (k= 0.466) when 528 human sera was detected by rF1 and natural F1. Conclusion We successfully extracted the rF1 with good immunological activity that might be used to detecting Yersinia pestis.

Assessment of comparative genomic hybridization experiment by an in situ synthesized CombiMatrix microarray with Yersinia pestis vaccine strain EV76 DNA / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>The quality of microarray data influences the accuracy of comparative genomic analyses to a large extent. To ensure that the results obtained by using an in situ synthesized microarray are accurate, data quality is to be assessed by evaluating the melting temperature (Tm) of probes, probability of false synthesis rates, and fragmentation of labeled targets.</p><p><b>METHODS</b>DNA from the Yersinia pestis vaccine strain EV76 was used for microarray analyses. Microarray results were confirmed by PCR. Statistical and bioinformatics methods were employed to perform microarray data analyses and evaluation.</p><p><b>RESULTS</b>Correlation coefficients of the three datasets were above 0.95 after two-time stripping and hybridization with a labeled DNA with the size of fragmentation being 200 bp - 2 kb, which showed that the hybridization results were highly reproducible. Correlation coefficients were lower with the values ranging from 0.87 to 0.92 between the datasets generated from hybridization with different sizes of the labeled DNA fragment. For the relationship between Tm and signal intensity, there was a different distribution of Tm in the lowest 300 or 3,000 probes with a range of 70 °C-72 °C and the highest 300 or 3,000 probes with a range of 72 °C-74 °C.</p><p><b>CONCLUSION</b>The results of this study suggest that the initial microarray design may affect the accuracy of final analyses and that the probe Tm and the size of the labeled fragment may be the two factors of the greatest importance.</p>

16S rRNA gene clone library analysis of bacterial communities of the tick with infection of 4 species of pathogens / 中国地方病学杂志

Objective To develop the method of 16S rRNA gene clone library for tick bacterial flora analysis, and to analyze the detection effective of pathogens in tick and capacity of bacterial flora diversity. Methods Primers were designed according to the specific gene of Borrelia burgdorferi, Bartonella henselae, Anaplasma phagocytophilum, Ehrlichia chaffeensis and templates were choosen by positive PCR result to amplify the DNA extracted from the ticks. One set of primers targeting 16S rRNA gene conserved region were chosen to amplify certain fragments, DNA extraction, PCR reaction, cloning and sequencing. Nucleotide sequences were compared with GenBank database. Calculated Coverage values of clone library and Shannon-Wiener diversity index. Results Sixteen defined genus-or species-bacteria were detected in 103 valid sequences. Eight species were edge type (Clone No. > 5). Three kinds of pathogens were identified (Borrelia burgdorferi, Bartonella henselae and Rickettsia sp). Three kinds of pathogens were not edge type(Clone No. < 5). Coverage value was 96.11%, and Shannon-Wiener index was 2.40. Analysis results of cloning sequence showed that tick-parasitic bacteria mainly were α and γ deformation mycetes which accounted for 56.25% (9/16). Conclusions The 16S rRNA gene sequences technology could make relative quantitative of bacterial flora, and detect many kinds of pathogens in tick. It's a good method for detection of pathogens and bacterial flora analysis.

Estimating rapid detection of F1 antigen of Yersinia pestis with gold-immunochromatography / 中国地方病学杂志

Objective To develop a rapid test for the detection of F1 antigen of Yersinia Pestis based on gold-immunochromatography.Methods F1 antibodies were coupled with colloidal gold to prepare collidal gold reagent,which was used to detect F1 antibodies based on double antigen sandwich.The collidal gold reagent was estimated for its sensitivity specificity and stablity in labs and 1798 samples were detected in 17 surveillance spots.Results The reagent was sensitive to 0.0010 g/L F1 antigens.The reagens kept stable when it had been placed at 4℃ or room-temperature for 12 months and did not react to Yersinia pseudotuberculosis and Yersinia enterolitica.In 17 surveillance labs the reagent was used to test 1798 viscera samples from animal.resulting an accordance rate of 97.11%(1746/1798)to bacterial culture and 96.83%(1741/1798)accordance to reverse indirect hemagglutination assay(RIHA),showing a higher detection rate[9.23%(166/1798)]compared with RIHA[6.79%(122/1798)]and bacterial culture[6.28%(113/1798)].Conclusions The collidal gold reagent,sensitive and specific in diagnosing Yersinia pestis infection of both human and animals,is a rapid method in surveillance spot.

Cloning and expression of the specific genes from Yersinia pestis and analysis of their antigenicity / 中国地方病学杂志

Objective To clone and express specific genes (YP01089,psi.ymt) from Yersinia pestis in Escherichia Coli(E.coli)and to analyze the antigenicity of these recombinant proteins.Methods The target genes were amplified by polymerose chmn reaction(PCR).The amplified products were ligated with pET-30a(+) vector after purification and cut by two different restriction enzymes,then these recombinant plasmids were transfefred into the host cells of E.coli BL21(DE3) strain.The target genes were successfully expressed following induction with Isopropyithio-β-D-galactoside(IPTG),and the target proteins were purified by the method of affinity chromatography.Sodium dodecyl sulfate-polyaerylamide gel eleetrophoresis(SDS-PAGE)and Westem blot were used to detect the expressed recombinant protein.Results Three recombinant plasmids were finally constructed. rYP01089,rPst and rYmt were expressed stably and effectively in E.coli thmngh optimizing the induction condition. The Western blot analysis indicated that rPst was capable of binding with positive sernm of phgue.The purity of rest was up to 95%in this stuay.Conclusions This work indicates that the genes of Yersinia pestis are able to be efficiently expressed in the prokaryotie protein expression system.The immune characteristic of rPst is sensitive and specific,80 this study has settled a foundation for developing a new type diagnostic reagent of plague.

Preliminary evaluation on the detection of serum level of antibody to Bacillus anthracis by enzyme-linked immunosorbent assay using crude antigen / 中国地方病学杂志

Objective To evaluate the method of detecting antibodies to Bacillus anthracis by enzymelinked immunosorbent assay(ELISA)using crude antigen.Methods The anti-Bacillus anthracis antibody levels in sera of 42 healthy people and 42 patients were detected by indirect ELISA.Standard curve was plotted using the data from positive controls,based on which the relative content of each serum was calculated and compared with the result of rLF.Results The median of antibody's relative content in patient group and healthy people group are 1.19 and 0.24,the differences being statistically significant(uc=7.643,P＜0.05).The result of crude antigen is in concordance with rLF(but not parallel absolutely).Conclusions Crude antigen can distinguish most of patients with healthy population effectively.The results suggested that crude antigen is applicable in anti-Bacillus anthracis antibody surveillance.

Locus-specific analysis of IS100 insertion within Yersinia pestis genome / 中国地方病学杂志

Objective To study the genotyping distribution of the Yersinia pestis(Y.pestis)strains by characterizing the diversity of the insertion sequence IS100 within the Y.pestis genome.Methods Derived fromthe known sequence of oriental strain CO92,5 pairs of locus-specific primers originating from both sides of the adjacent region of IS100 copies were designed,and two other complementary primers inside the IS100 sequence were designed to correspond with the outer primers.Then,91 Y.pestis strains and l pseudotubebculosis strain were tested by the specific PCR method using the primers described above and the PCR products were conformed by the sequence analysis,then further analysis WaS performed after the IS100 status was marked on the map of the plague focus type of china.Results The 91 Y.pestis strains had different IS100 status in their genome on tested loci.some possessed IS100 insertion,some didn't,and others changed their genome constitution.The IS100 possession on the 5 loci also suggested a distribution of regionality.Conclusion The analysis of some IS100 insertion element loci reveals that the IS100 genotyping distribution is consistent with the plague focus of type of China.And IS100genotyping pattern of the Y.pestis stains well reflects its genome constitution and the high flowability in its natural evolution.

Study on the application and evaluation of methods for gene and antigen detection in plague surveillance program / 中华流行病学杂志

<p><b>OBJECTIVE</b>To apply and evaluate new methods regarding specific gene and antigen detection in plague surveillance program.</p><p><b>METHODS</b>1798 samples from natural foci of plague were tested, using internal quality control multiple-polymerase chain reaction, F1 antigen marked by immuno chromatographic assay and enzyme linked immunosorbent assay. Culture of Yersinia pestis and reverse indirect hemagglutination assay were used as reference diagnostic methods.</p><p><b>RESULTS</b>The overall positive rate of culture on Yersinia pestis together with gene and antigen detection was 7.34%, showing an 16.81% increase when comparing to 6.28% using Yersinia pestis culture method alone. The rate of coincidence was 97.13%.</p><p><b>CONCLUSION</b>The new standard being used for specific gene and antigen detection could increase the positive rate of diagnosis on plague.</p>

Use of variable-number tandem repeats to examine genetic diversity of Bacillus anthracis / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the genotyping of Bacillus anthracis based on multiple-locus variable-number tandem repeats(VNTR) in the B. anthracis genome.</p><p><b>METHODS</b>We selected 13 VNTR loci (which cited from published articles) to study 88 strains of B. anthracis isolated from China. The methods used were: (1) Selecting the primers which were at both ends of the tandem repeat locus; (2) Amplifying the sequence of the locus by PCR; (3)cDetecting the PCR products by agarose gel and polyacrylamide electrophoresis; (4)Analyzing the PCR products and computing the molecular weight by analysis software of gel images;(5) Double-checking with sequencing results; (6)Reckoning the repeat numbers and study the VNTRs loci characters.</p><p><b>RESULTS</b>(1) We used multiple-locus variable-number tandem repeat analysis (MLVA) to characterize 88 B. anthracis isolates from diverse geographic locations which were divided into 45 MLVA genotypes and 3 groups through cluster analysis. The genotypes was relative to restricted geographical region. It seemed clear that the multiple isolates from the same anthrax outbreak frequently having identical genotypes. (2)Results from VNTR analysis showed that A16R vaccine strain isolated from China was having the nature of representativeness in the country.</p><p><b>CONCLUSION</b>Analysis showed that the VNTR patterns was an appropriate study method for B. anthracis genetic diversity from different geographical areas and different time. Isolates from the same anthrax outbreak had identical</p>

Surveillance on severe acute respiratory syndrome associated coronavirus in animals at a live animal market of Guangzhou in 2004 / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the prevalence of severe acute respiratory syndrome coronavirus (SARS-CoV) like virus in animals at a live animal market of Guanzhou in 2004 before and after culling of wild animal action taken by the local authority, in order to predict the re-emerging of SARS from animal originals in this region.</p><p><b>METHODS</b>Animals at live animal market were sampled for rectal and throat swabs in triplicate. A single step realtime reverse transcription-polymerase chain reaction (RT-PCR) diagnostic kit was performed for screening SARS-CoV like virus, the manual nested RT- PCR and DNA sequencing were performed for confirmation. Only specimens which tested positive for both of the N and P genes by nested RT-PCR were scored as positive.</p><p><b>RESULTS</b>In 31 animals sampled in January 5 2004 before culling of wild animals at Guangdong Province, including 20 cats (Felis catus), 5 red fox (Vulpes vulpes) and 6 Lesser rice field rats (Rattus losea), 8 (25.8%) animals were tested positive for SARS-CoV like virus by RT-PCR methods, of which 4 cats, 3 red fox and one Lesser rice field rats were included. However, two weeks after culling of animals and disinfection of the market were implemented, in 119 animals sampled in January 20 2004, including 6 rabbits (Oryctolagus cuniculus), 13 cats, 46 red jungle fowl (Gallus gallus), 13 spotbill duck (Anas platyrhynchos), 10 greylag goose (Anser anser), 31 Chinese francolin (Franclinus pintadeanus), only rectal swab from one greylag goose was tested positive for SARS-CoV like virus. Furthermore, in 102 animals that including 14 greylag gooses, 3 cats, 5 rabbits, 9 spotbill duck (Anaspoecilorhyncha), 2 Chinese francolin (Franclinus pintadeanus), 8 common pheasant (Phasianus colchicus), 6 pigeons, 9 Chinese muntjac (Muntiacus reevesi), 19 wild boar (Sus scrofa), 16 Lesser rice field rats, 5 dogs, 1 mink (Mustela vison), 3 goats, 2 green peafowl (Pavo muticus) sampled in April, May, June, July, August and November, only rectal swab from one pig was tested positive. However, of 12 and 10 palm civets sampled in November and December including five of which had been at the live animals market for 2 days, none of them was tested positive.</p><p><b>CONCLUSION</b>This findings revealed that animals being sampled in April, May, June, July, August and November of 2004, only one rectal swab from a pig was tested positive as SARS-CoV like virus, much lower than the results from the previous year, suggesting that the possibility of re-emerging of human infection from animal origins is low for the winter of 2004-2005.</p>

Study on the internal control on polymerase chain reaction in Yersinia pestis detection / 中华流行病学杂志

<p><b>OBJECTIVE</b>For the detection of Yersinia pestis by polymerase chain reaction (PCR), internal control (IC) is required in order to prevent false negative results that might be caused by PCR inhibitors.</p><p><b>METHODS</b>F1 antigen was amplified by PCR with primer F1 and the PCR product of primer F1 were cloned with TOPO TA cloning Kit. The plasmid of positive clone was then digested with HpaI. The digested plasmid and the PCR products of 16S rRNA were ligated with T(4) DNA ligase before the ligated products were transformed. Isolate plasmid DNA on positive clone and its concentration were measured. Plasmid DNA on different concentration by PCR amplification with primer F1 was analyzed and the standard concentration of IC was determined.</p><p><b>RESULTS</b>Constructing an IC by inserting a 16S rRNA amplicon to the original target DNA between the two primer F1 sites, the size was longer than the target DNA. The standard concentration of IC was determined.</p><p><b>CONCLUSION</b>An optimal IC concentration to increase the reliability of the PCR assays might be used to prevent false negative results and appeared to be useful for detection of Yersinia pestis.</p>

Establishment and application of real-time fluorescence polymerase chain reaction based on the TaqMan probes for detection of Yersinia pestis / 中华流行病学杂志

<p><b>OBJECTIVE</b>Establishing and developing methods for quick, special and of Yersinia pestis (Y. pestis).</p><p><b>METHODS</b>Using real-time fluorescence polymerase chain reaction (PCR) based on TaqMan technology with UDG anti-contamination systems and ROX reference dye, we established a method to detect Y. pestis. Probes and primers from pla, caf1, hms and inv gene were designed. An internal positive control was added to the reaction mixture in order to detect the presence of PCR inhibitors that were often found in biological samples. Sensitivity was evaluated by serial dilution of colons, internal template and Y. pestis strains while specificity was confirmed by amplifying real DNAs from bacteria, the representative Y. pestis strains and blind assay.</p><p><b>RESULTS</b>The methods used could provide quick, special and sensitive detection of Y. pestis, with sensitivities of pla, f1, hms as 10, 1 and 1 copie(s) respectively.</p><p><b>CONCLUSION</b>The newly developed technologies seemed to be well suited to identify the Y. pestis in case of emergency, bio-terrorist attack and surveillance of the epidemics.</p>

Study on Bartonella infection using molecular biological diagnostic techniques from China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To establish polymerase chain reaction (PCR) technique for the detection of specific genes related to species of genus Bartonella, and for diagnosing clinically suspected cat-scratch disease (CSD) case complicated with pneumonia on both lungs. The appearance of Bartonella infectious diseases calls for genus and species detection and tools for identification in order to make clinical diagnosis and carry on epidemiological studies.</p><p><b>METHODS</b>One pair of primer TIle.455p-TAla.885n was designed based on the fact that tRNA(Ile)-tRNA(Ala) intergenic spacer region in 16S-23S rRNA intergenic spacer (ITS) of genus Bartonella were high variable sequences flanked by completely conserved tRNA-encoding genes. 16S-23S rRNA was longer than that which had been described in other bacteria. Two published pairs of primers were used to directly detect the specific gene fragments of Bartonella species DNA extracts from human blood, followed by PCR product Sequencing and nucleotide base sequence analysis.</p><p><b>RESULTS</b>Amplification products of the three pairs of primers had the same predicted size of those in Bartonella spp. According to the different length of electrophoresis bank, the sample was identified as a species of genus Bartonella other than the positive control. Sequence analysis showed that the nuleotide sequence from the PCR product of primer TIle.455p-TAla.885n was identical to the Bartonella isolated from Yunnan in China.</p><p><b>CONCLUSIONS</b>PCR-based assay provided a simple and rapid means to detect pathogenic Bartonella species in humans and mammalian hosts as well as in arthropod vecters. This study suggested that this pathogenic Bartonella species existed in patients in northern and southern parts of China.</p>

Study on the prevalence of Bartonella species in rodent hosts from different environmental areas in Yunnan / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate Bartonella infections in small mammalian reservoir hosts from different environments and types of climate in Yunnan.</p><p><b>METHODS</b>Femoral blood samples were collected from the anesthetic captured animals from five counties including three types of climate. All isolates were grown on brain and heart infusion agar plates containing 5% defibrinated rabbit blood. The agar plates were incubated at 35 degrees C in a humidified with 5% CO2 environment for at least 4 weeks. Bartonella-like isolates were confirmed by the polymerase chain reaction and visualizing the target gene fragment by gel electrophoresis.</p><p><b>RESULTS</b>Bartonella species were isolated from 69 of 176 small animals including 4 species of 3 genera from 4 counties and the total prevalence in rodents was 39.2%. The maximal prevalence was 42.0% of Rattus tanezumi flavipectus usually inhabiting indoors and courtyard and contacting closely to human. Moreover, Bartonella isolates were obtained from Rattus noruegicus, Eothenomys miletus and Mus pahari. Life environments of captured animals involved indoors, courtyard, brush and forest in mountain.</p><p><b>CONCLUSION</b>The finding in this study suggested the characteristic of diversity of Bartonella infections in rodent hosts in southern China included Bartonella species parasiting in a wide range of animal hosts in different environments as well as climate types. Further investigations were needed in different areas in China to confirm more mammalian reservoir hosts with Bartonella infections.</p>

Study on the relation between the absence of one IS100 in 102 kb pgm locus of Yersinia pestis and the stability of pigmentation phenotype / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the relation between the absence of one IS100 in the 102 kb pgm locus of Yersinia pestis and the stability of pigmentation phenotype (pgm(+)).</p><p><b>METHODS</b>We amplified the segment including IS100 in 102 kb pgm locus of Yersinia pestis that isolated from all ecotypes in China by polymerase chain reaction (PCR). There were 171 strains isolated from 18 ecotypes in this study. One strain was chosen to be cloned and sequenced.</p><p><b>RESULTS</b>Besides the type of Microtus brandti, the types of East-North Tianshan, A and B of West-North Tianshan, Microtus Qinghai had one band with about 2560 bp. These strains lost one IS100 in 102 kb pgm locus of Yersinia pestis. Their pgm(+) phenotype was stable. Some strains of ecotypes from Qilian Mountain, Qinghai-Tibet Plateau, Gangdisi Mountain, West Yunnan Mountain had no bands in the PCR products. Negative strains would lose the whole 102 kb pgm locus. The others had one band with 4492 bp. These strains had two IS100 which flanked the 102 kb pgm locus but the pgm(+) phenotype was unstable.</p><p><b>CONCLUSION</b>Yersinia pestis which had only one IS100 would flank the 102 kb pgm locus and had stable pgm(+) phenotype while the Yersinia pestis that having two IS100 flanked the 102 kb pgm locus would have unstable pgm(+) phenotype.</p>

Molecular biological characteristics and genetic significance of Yersinia pestis in China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To understand the molecular biological characteristics in order to analyse the genetic background of Yersinia pestis in China.</p><p><b>METHODS</b>Primary datum on ribotyping, pulsed field gene electrophoresis (PFGE), random amplified polymorphic DNA (RAPD) and insertion sequence (IS) of Yersinia pestis were used and under cluster analysis. Genetic interval and various methods of recognized molecular feature between different strains were evaluated.</p><p><b>RESULTS</b>Ribotypes the PFGE types seemed to be corresponding. Stains from Microtus fuscus and area in Tibet Zhongba belonged to 7 copy rRNA gene and the genetic interval were the far more with 6 copy rRNA gene stains, and not definite with RAPD, but with many exceptions. The genetic interval between strains were showed by resemble value.</p><p><b>CONCLUSION</b>Yersinia pestis in China had its own manifold, particular molecular biological characteristics due to natural barriers, geographical complex, circumstances in Tianshan Mountains and Gandise Mountains areas. Yersinia pestis were limited to separateness, evoluted only in certain areas to form a great many gene types.</p>