To further study the structure and nature of the foci of plague in Hebei province, this article summarizes the biological characteristics of Yersinia pestis isolates in the regions by analyzing the large amounts of data collected. By introducing the biochemical characteristics, nutritional needs, plasmid characteristics, virulence factors, virulence and toxins and other aspects, the study has concluded that Y. pestis isolated in Hebei province belongs to Group B of the Ordos Plateau, of which the nutritional needs are characterized by glycine semi-dependence and tryptophan dependence. These strains contain 4 kinds of plasmids, of which 13×106 plasmid is specifically carried by Meriones unguiculatus in the Inner Mongolian. Some strains lack the 45×106 plasmid, though all of isolates were F1 antigen and streptozotocin (PstⅠ)-positive. However, only a certain portion of the strains were positive for pigmentation (Pgm) and VW antigen, indicating genetic instability and moderate toxicity.

Objective To determine the feeding habits of Spermophilus dauricus Brandt in the north frontier administration areas of Hebei province, providing the basis for plague prevention and control as well as rodent damage assessment. Methods The S. dauricus Brandt of different habitats were captured and randomly sampled by male, female, adult and infant. The subjects’stomachs were weighed, and dissected for analysis of the contents and respective proportion of the components. Results The average stomach weight was 10.48 g, and the maximum was 40.50 g. A total of 80% of the sample stomachs contained mainly the green parts of plants, 7% contained mainly seeds and rootstalks, and 9% contained mostly insects. Different composition of the stomach contents was noticed between June and July and between adults and infants, albeit not found between males and females. Conclusion S. dauricus Brandt has a big appetite and intakes mainly vegetable foods, including agricultural crops and the green parts of pasture, and often insects, seeds and rootstalks. The food composition varies with environment.

【Abstract】 Objective To study  the  practicability  of  double  antigens  sandwich  enzyme  linked  immunosorbent  assay（DAgS?ELISA）on the detection of Yersinia pestis F1 antibodies. Methods A total of 558 samples antibodies of anti?F1 antigen were detected by DAgS?ELISA and trace indirect hemagglutination assay (trace?IHA). Results Thirty three samples were positive tested by IHA, 31 positive by DAgS?ELISA, the positive accordance rate was 90.91%, 99.81% for negative accordance rate, 99.28% for the total accordance rate. The positive rate detected by IHA and DAgS?ELISA were 5.91% and 5.56% respectively, and no statistics difference was found (χ2＝0.25，P＝0.625). About 27 the immuno?serum were positive detected by IHA and DAgS?ELISA methods, and the sensitivity of IHA test were all higher than that of DAgS?ELISA (t＝3.023, P＝0.006). Conclusion Sensitivity of DAgS?ELISA is lower than that of trace?IHA, but its specificity is better and no primary inhibitory phenomena, and could exempt from leak detection in the preliminary screening.

【Abstract】 Objective To establish the control measure of plague in Hebei, and provide science evidence for the early warning of plague epidemic situation. Methods The data of mice plague outbreak collected from the plague nature foci was analyzed. Results The epidemic characteristics and epidemic regularity  of  plague were clarified. Conclusion Epidemic of plague had the characteristics of sudden occurrence, wide epidemic range, great intensity, the obvious increase of main hosts quantity and the trend expanding to town and impacted areas.

Objective To study the sensitivity of colloidal gold immunobinding and analyze the distribution of crowd bubonic plague F1 immune body in Hebei province.Methods 196 serums and 162 serums of healthy people were sampled from history areas affected by plague and plague foci among animals(Zhangjiakou city) in Hebei natural plague foci and fur processing workers in Baoding.100 serums were collected from non-plague foci as control.Colloedal gold immunobinding and indirect hemagglutination test(IHA) were used to detect,at the same time,the minimum limit of detection of these two methods was compared.Results There were 3 positive serums in 196 serum samples,and the positive rate was 1.53%.None positive samples was found in 162 serum samples.The control were all negative.Conclusion The minimum detection of colloedal gold immunobinding was less than that of IHA.There were positive serum samples in plague natural foci,and the people age whose serum presented positive exceeded 40 years old.The samples collected from Baoding fur processing workers and non-plague foci were all negative.2 samples were positive after vaccination by investigation,and others needed be further explored.

Objective To study the distribution of plague F1 antibody from coat-processor blood serum in the coat market of Li county, Baoding city. Methods To detect 162 blood serums sampled statistically from coat-processor with indirect hemagglutination assay(IHA) and colloedal gold immunobinding, and 63 blood serums collected from non coat-processor as control. Results 162 blood serums were all negative, accordant with the control. Conclusion There was no plague recessive in coat-processor from coat market of Li county, Baoding city.

Objective To study the three-dimensional distribution and maintenance mechanisms of plague F1 antibody of healthy population in the plague natural foci of Hebei province. Methods To sample 196 blood samples from three administrative villages belonging to plague natural foci formerly, and collect 100 blood samples from non-infected areas as the control. Indirect hemagglutination test(IHA) and colloedal gold immunobinding were used in this test. Results There were 4 positive among 196 blood samples, and the positive rate was 2.04%. There were 4 positive samples in IHA and 3 positive samples in colloedal gold immunobinding. The human serums collected from non-infected areas were all negative after tested by theses two methods. There was significant difference between the positive rate of F1 antibody in epidemic areas and the positive rate of F1 antibody in non-epidemic areas ( χ ₂=0.822, P<0.05). Conclusion At present, there are still a number of F1 antibody positive population in the natural epidemic focus of Hebei, and it needs further investigation and analysis to clarify.

Objective:To research on the biological and epidemiological characteristics of 115 Y.pestis.Methods:Detection of virulent factors.etc.Result:Isolated from different foci and reservoirs in Northern Hebei and in middle Inner Mongolia,115 strains of Y.pestis have been performed with permentation of alcohol and carbohydrate,nitrate reduction,urea decomposition,indigo formution and virulent factors etc.Conclusion:The results have showed differences of relative stability brom phenotypic charactors because of different natural foci.According to Chinese Y.pestis ecotype,they belong to Erduosi Plateau.

This is a report that characteistics of freeze-diying preserved Yersinia pestis were tested, including colonial morphology, somatic morphology, test of phagocytosis, biochemistry and sensitivity to antibiotics. These results showed that freeze-dzying could stably maintain characters of Y.pestis forever. It couldn't affect biochemical character and sensitivity to antibiotics of Y.pestis. Somatic morphology, colonial morphology and phagocytosis test of freezedried Y. pestis were the same as before, but only a few strains had a bit differences. So this is the best method to preserve Y.pestis.