Epidemiological analysis of the human plague from 2001 to 2011 in Qinghai Province / 中国地方病学杂志

Objective To analyze human plague from 2001 to 2011 in Qinghai Province and to provide a scientific basis for formulating prevention and control measures.Methods Using the descriptive epidemiological methods,epidemiological field survey data and medical records of each case of human plague were collected from 2001 to 2011 in Qinghai Province.Human plague was judged in accordance with the Plague Diagnostic Criteria (WS 279-2008).Results From 2001 to 2011,human plague was reported 14 times,with incidence of 38 cases,17 dead and death rate was 44.74％ in Qinghai Province.Epidemic areas mainly distributed in the 12 townships of 9 counties.Prevalent season was from May to October,September and October accounted for 57.89％ (22/38).There were cases of Tibetan herders and Han farmers,accounting for 76.32％ (29/38) and 23.68％ (9/38),respectively;onset age from 5 to 67 years,mainly around the age of 20-45 [68.42％ (26/38)].The most prevalent clinical types were pneumonic and septicemic plague and initial case was caused by actively contact with infected plague animals.Conclusions Qinghai human plague is mainly caused by approaching the plague infected animals,human plague in Qinghai Province is on the rise,the risk of long-distance transmission of the plague is significantly increased.

Different strategies for preparation of non-tagged rV270 protein and its efficacy against Yersinia pestis challenge / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>LcrV is an important component for the development of a subunit vaccine against plague. To reduce immunosuppressive activity of LcrV, a recombinant LcrV variant lacking amino acids 271 to 326 (rV270) was prepared by different methods in this study.</p><p><b>METHODS</b>A new strategy that produced non-tagged or authentic rV270 protein was designed by insertion of rV270-thrombin-hexahistidine fusion gene into the vector pET24a, or by insertion of hexahistidine-enterokinase-rV270 or hexahistitine-factor Xa-rV270 fusion gene into the vector pET32a. After Co(2+) affinity chromatography, a purification strategy was developed by cleavage of His tag on column, following Sephacryl S-200HR column filtration chromatography.</p><p><b>RESULTS</b>Removal of His tag by thrombin, enterokinase and factor Xa displayed a yield of 99.5%, 32.4% and 15.3%, respectively. Following Sephacryl S-200HR column filtration chromatography, above 97% purity of rV270 protein was obtained. Purified rV270 that was adsorbed to 25% (v/v) Al(OH)₃ adjuvant in phosphate-buffered saline (PBS) induced very high titers of antibody to rV270 in BALB/c mice and protected them (100% survival) against subcutaneous challenge with 10⁶ CFU of Y. pestis virulent strain 141.</p><p><b>CONCLUSION</b>The completely authentic rV270 protein can be prepared by using enterokinase or factor Xa, but they exhibited extremely low cleavage activity to the corresponding recognition site. Thrombin cleavage is an efficient strategy to prepare non-tagged rV270 protein and can be easily operated in a large scale due to its relatively low cost and high cleavage efficacy. The recombinant rV270 can be used as a key component to develop a subunit vaccine of plague.</p>

Evaluation of immunization protection efficacy of plague subunit vaccine / 中华预防医学杂志

<p><b>OBJECTIVE</b>To evaluate the protective efficacy of plague subunit vaccine, BALB/c mice, guinea pigs and rabbits were used in this study.</p><p><b>METHODS</b>Groups of mice (10 per group), guinea pigs (14 per group) and rabbits (6 per group) were immunized with F1 + rV270 vaccine, EV76 vaccine and alum adjuvant by intramuscular route, respectively. Serum antibody titres of mice, guinea pigs and rabbits were determined by ELISA and the immunized animals were challenged with 10(6) CFU of Y. pestis strain 141 at the 8th week after the primary immunization.</p><p><b>RESULTS</b>The immunized mice, guinea pigs or rabbits with subunit vaccine developed anti-F1 IgG titre of 41 587.3 +/- 2.1, 11 543.7 +/- 2.1 or 522.4 +/- 22.4 and elicited statistical anti-F1 IgG titre difference among them (F = 17.58, P < 0.01). The immunized mice, guinea pigs or rabbits with subunit vaccine had anti-rV270 IgG titre of 15 748.7 +/- 1.6, 12.6 +/- 1.4 or 1648.0 +/- 5.0 and induced statistical anti-rV270 IgG titre difference among them (F value was 16.34, P < 0.01). There was significant anti-F1 IgG titre difference among mice, guinea pigs and rabbits immunized with EV76 vaccine that developed anti-F1 IgG titre of 913.4 +/- 4.5, 937.0 +/- 2.0 or 342.0 +/- 12.0 (F = 23.67, P < 0.01), whereas the immunized mice, guinea pigs and rabbits with EV76 vaccine developed anti-rV270 IgG titre of 12.0 +/- 1.0, 447.0 +/- 10.0, 40.0 +/- 11.0 and there was no anti-rV270 IgG titre difference between them (F = 2.20, P = 0.1314). The immunized mice with subunit vaccine developed significantly higher anti-F1 IgG titres than immunized guinea pigs and rabbits (q value was 30.57 and 19.04, respectively, P < 0.01), and there were no anti-F1 IgG titre differences between the immunized guinea pigs and rabbits (q = 0.04, P = 0.8485). The immunized mice with subunit vaccine developed significantly higher anti-rV270 IgG titres than immunized guinea pigs and rabbits (q value was 27.10 and 19.49, respectively, P < 0.01), and there were no anti-rV270 IgG titre differences between the immunized guinea pigs and rabbits with the subunit vaccine (q = 0.25, P = 0.6187). The immunized mice with EV76 elicited higher anti-F1 IgG titres than immunized guinea pigs and rabbits (q value was 40.67 and 29.10, respectively, P < 0.01), whereas there was no difference of F1 IgG titer between immunized guinea pigs and rabbits (q = 0.06, P = 0.8098). The immunized mice, guinea pigs and rabbits with subunit vaccine provided 100% (10/10), 86% (12/14) and 100% (5/5) protection against 10(6) CFU Y. pestis of challenge, respectively. The immunized mice, guinea pigs and rabbits with EV76 vaccine gave 100% (6/6), 93% (13/14) and 100% (6/6) protection against 10(6) CFU Y. pestis of challenge respectively.</p><p><b>CONCLUSION</b>BALB/c mice is the best small animal model for valuation of protective efficacy of plague subunit vaccine. The guinea pigs showed a high individual variation for this purpose. The rabbits can be used as an alternative model for evaluating plague subunit vaccine.</p>

Identification of 2 strains of suspected Yersinia pestis isolated from Marmot,,himalayana in Dege County,Sichuan Province / 中国地方病学杂志

Objective Throush identify biochemical characteristics and virulence factors of 2 strains suspected Yersinia pestis(Y.pestis)isolated from the dead Marmota himalayana(M.himalayana)to confirm the nature epidemic focus in Dege County,Sichuan Province.Methods Y.pestis was analyzed by specific staining and shape,culturing characteristics,splitting-test by bacteriophage,test of biochemical characteristics and glycolysis ability,virulence factors,virulence,nutritional requirement,plasmid,genetic test and genetic type. Results The tested strains were Gram staining bacilus.The main biochemical characteristics were Arabinose(+)、 Rhamnose(-),Maltose(+),Melibiose(-),Glycerol(+),Denitrification(+).The virulence factors with FI+.VW+, Pgm+,Pst I+;and with the common 6.0×106,45.0×106,65.0×106 plasmids,also with the virulence-relative plasmid gene.Both their absolutely lethal dose(LD100)in mice were 50 bacteria.The nutritional requirement appeared which were depended on Phenylalanine and Methionine.With the Genomovar 5 genotype characteristics of M.himalayana plague foci of Qinghai-Tibet plateau.The difference between tested strains and Yersinia pseudotubercuosis on the 3 different culture medium was obvious.The tested strains had a Y.pestis' specific 3a fragment,Pst I and FI-Ag,at 22 ℃,the strains could be split by bacteriophage completely.Conclusions According to the diagnostic criteria of plague in China,the 2 suspected strains isolated from Dege County,Sichuan Province ale confirmed as Y.pestis.both with powerful virulenceand with the characteristics of the Y.pestis of M.himahtyana in Qinghai-Tibet plateau plague natural focus.

Investigation on the space structure of plague natural foci in the Sanjiangyuan area in Qinghai Province / 中国地方病学杂志

Objective To investigate the space structure of plague natural foci in the area of Lantsang, Yellow and Yangtse River in Qinghai Province to provide references for making decisions to eontrol the occurrence of human plague. Methods Data was collected from the survey on natural foci and surveillance of plague from 1954 to 2006 and descriptive epidemiological method was used to analyze the data. Results Marmata hirnalayana and Microtus fuscua natural foci were known in Sanjiangyuan area. Callopsylla dolabris, Oropsylla silantiewi, Citellophilus sparsilis and Amphipsylla tuta were vectors; Microtus fuscus plague natural foci was in a range of about 9500 km2, distributing in Zhenqin Town, Chengduo County. Marmata himalayana plague natural foci distributed over 13 countries, a range nearly 107 000 km2. By the end of 2006, 450 strains of Yersinia pestis were detected and separated from 6 kinds of rodents, 6 kinds of carnivora, 3 kinds of artiodactyls and 9 insects vectors. Between 1960 and 2006, 238 cases and 134 deaths from plague were reported. Most human plague cases occurred in the months from May to November and usually presented as one of three primary forms-bubonic 17.23%(41/238), septicemic 16.81% (40/238), pneumonic 61.34% (146/238) and other types 4.62% (11/238). However, the first epidemic plague case was mainly the glandular plague. Conclusions Date suggested that plague is still a critical public health problem in Sanjiangyuan area, against which countermaeasure needs to be strengthened in the main epidemic areas. More scientific researches on plague should be carried out. Surveillance networks of reporting suspected plague have been established and reduce the number of human plague cases.

Analysis the epidemiology and clinical feature of plague cases from 1981 to 2006 year in China / 中国地方病学杂志

Objective To summarize the epidemiological feature of plague cases oceuwed in China.Methods The epidemiological and clinical data from 1981 to 2006 year in China were analyzed with descriptive study method.Result Nine hundred and seveneteen human plague cases were diagnosed in 9 provinces(regions) from 1981 to 2006 years,105 cases died,the mortality rate being 11.45%,and they distributed in 69 counties (cities or banners).In Qinghai Province 108 cases were diagnosed,the mortality rate was 46.30%(50/108),the cases distributed in 17 counties(cities);137 cans in Guizhou,distributing in 2 counties(cities);517 cases in Yunnan,distributing in 26 counties(cities).Plague cases peaked separately in 1983,1990,1996 and 2000 years,they were 25,75,98 and 254 separately.The principal spreading ways were breathing flying particles,touching,skinning and eating marmot in Qinghai;750 cases were of bubonic plague,among whom 4 cases in Tibet died,the fatality rate was 0.53(4/750);121 cases were of pneumonic prague,among whom 65 cases died,was accounting for 53.72%(65/121);31 cases were of septieaemic plague,and 30 cases died(one cases was cured in Inner Mongolia),accounting for 96.77%(30/31).Others were brain plague,intestinal plague,tonsil plague and plague cellulites,which were cured.Conclusion From 1990,human plague epidemical scope and intensity is enlarging continuously compared with 1980-1990 and there is a trend of going up gradually in China.

Epidemiologic analysis on human plague of Sanjiangyun Area in Qinghai Province, China / 中国地方病学杂志

Objective To study on epidemiologic characteristics of human plague cases in Sanjiangyuan Area,and provide theoretical basis to work out the preventive measures.Methods Based upon the epidemiology information from the human plague case data bank of Qinghai Province,human plague data were analyzed retrospectively in Sanjiangyun Area by sorting,verifying and summing up of these data,including some of case file and monitoring data.Results Except for 12 years in the period of 1960 to 2006,there were human plague cases happened every year.The morbidity occurred mainly in 12 counties of 4 states,including Yushu,Guolou,Huangnan and Hainan,and Tanggula Town of Geermu City,a total of 85 human plague episodes were occurred,resulting 238 onsets,134 deaths,and a matality rate of 56.30%.The sources of infection were respectively Himalayan mormot 27.31%(65/238),artiodactyls 14.71%(32/238),carnivora 2.10%(5/238),Lagomorpha 0.42%(1/238),the pneumonic plague patient 49.16%(117/238),and biting of flea 6.30%(15/238).The prevalent season was from May all the way to November,the peak-months were August and September.After October,the sheep as the source of infection initiating human being plague accounted for 23.53%.Among the clinical types,the most prevalent type was pneumonic type(61.34%),and the rest,glandular type(17.23%),septic type(16.81%)and other types(4.62%),but the first plague case in each epidemic was mainly the glandular plague.Conclusions In recent years,the tendency of human plague prevalence increases in Sanjiangyuan Area,it is urgent to improve and adjust the prevention and treatment measures in time.

Genetics comparison on the Yersinia pestis strains of 3 kinds of ecotypes in the Sanjiangyuan area, Qinghai Province / 中国地方病学杂志

Objective To compare the genetic polymorphism of 34 Yersinia pest strains of 3 kinds of ecotypes(Microtus fiscis,Qilian Mountain and Qinghai-Tibet Plateau ecotype)that isolated from the Sanjiangyuan area in Qinghai Province and Shiqu County in Sichuan Province,in order to know the ecotype relationship among the strains.Methods Thirty-four strains were amplified using the application of random amplified polymorphism DNA(RAPD)and were detected with agaroge gel electmphoresis.Results Amplified products by ngarose gel electrophoresis method showed same stripes in 31 strains,only 3 strains had slight differences.Conclusion The Microtus fuscas,Qilian Mountain and Qinghai-Tibet Plateau ecotype strains isolated from Sanjiangyuan area are genetically homologous.

Study on the genotyping and microevolution of Yersinia pestis in the Qinghai-Tibet Plateau / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the distribution of genomovars and microevolution of Yersinia pestis in the Qinghai-Tibet Plateau.</p><p><b>METHODS</b>Primer pairs targeting the twenty-two different regions(DFRs) were designed for detecting the presence or deletion of each DFR in 297 strains isolated from the Qinghai-Tibet Plateau.</p><p><b>RESULTS</b>9 genomovars, i. e. Genomovar 1, 5, 6, 7, 8, 10, 11, new type and Ype-ancestor were identified in the Marmota himalayana plague focus of the Qinghai-Tibet Plateau. Among these genomovars, genomovar 5,8 and 10 were dominant types. The total rate of the three genomovars was 80.6% (204/253) and the genomovars in different regions were different. All of 44 strains of Y. pestis in the Microtus fuscus plague focus of the Qinghai-Tibet Plateau belonged to genomovar 14.</p><p><b>CONCLUSION</b>The distribution of genomovars of Y. pestis in the Qinghai-Tibet plateau had remarkable characteristics geographically. Based on the distribution of genomovars of Y. pestis, the routes of transmission and microevolution of Y. pestis were proposed.</p>

Genetic analysis of Yersinia pestis strains isolated in China / 中华流行病学杂志

<p><b>OBJECTIVE</b>The strains of Yersinia pestis isolated in different period and different natural foci in China were analyzed.</p><p><b>METHODS</b>Traditional and molecular biological methods were used. Rhamnose fermentation, rRNA gene copy number, nitrite reduction, and the glycerol fermentation were important characters for typing, and pulse field gel electrophoresis (PFGE) and random amplified polymorphic DNA (RAPD) profile could reflect the genetic distance between the strains.</p><p><b>RESULTS</b>The strains could be divided into 15 genetic types by those 6 characters with each of them covered an isolated geographical territories.</p><p><b>CONCLUSION</b>The characters of strains were described; the genetic relationship of different types, their evolution, and the forming and shift of plague natural foci were analyzed.</p>