ABSTRACT
Objective@#To observe the dynamics of antibody response in great gerbils infected with Yersinia pestis in experiment.@*Method@#A total of 211 great gerbils were captured in the southern margin of plague natural focus of Junggar Basin of the Xinjiang Uygur Autonomous Region in 2011. Among them, there were 167 great gerbils without infection of Y. pestis and 44 great gerbils infected by Y.pestis. Y.pestis No. 2504 was employed for this experimental strain, which was strong toxic strain with negativity in the reduction experiment of nitrate. 35 great gerbils without the infection of Y. pestis were divided randomly and averagely into 7 groups including 6 experimental groups and 1 control group. Great gerbils in the 1st to 6th experimental groups were exposed first with 1 × 106-1 × 1011 CFU/ml of bacterial fluid with 10 times of gradient dilution; groin areas of great gerbils in the control group were injected subcutaneously with physiological saline; and the amount of infection was all 1 ml. 17 great gerbils infected with Y. pestis and the first detection of F1-antibody titer in 1∶256-1∶4 096 were grouped according to F1-antibody titer: group 1∶4 096 (n=4), group 1∶2 048 (n=4), group 1∶1 024 (n=3), group 1∶512 (n=3) and group 1∶256 (n=3); and blood in caudal regions was collected in asepsis for the detection of F1-antibody, with a total of 5 times. 9 great gerbils which were selected from the remaining great gerbils infected with Y. pestis and detected F1-antibody negative 2 times were exposed 1×106 CFU/ml of bacterial fluid for the second infection, with the amount of infection being 1 ml. Blood in caudal regions of great gerbils after the first and second infection were collected for the detection of plague F1-antibody on the 3rd, 5th, 7th, 15th, 30th, 60th, 90th and 120th day after infection. Declined regression models for great gerbils' antibodies were established with unary linear regression equation; declined change diagrams for the antibodies were drawn to observe the declined F1-antibody after great gerbils were exposed to Y. pestis.@*Results@#In great gerbils with the first infection of Y. pestis, antibodies were detected in the 1 × 106-1 × 108 CFU/ml of group on the 30th, 15th and 15th day, respectively; the positive rates of antibody were 1/4, 3/4 and 4/5, respectively; the group 1×107 and 1× 108 CFU/ml reached to the highest antibody titer with 1∶256 on the 120th day; antibodies were revealed in the group 1×109, 1×1010 and 1×1011 CFU/ml from the 5th to 7th day when the seroconversion of all antibodies was observed; group 1×1011 CFU/ml reached to the highest antibody titer on the 120th day with 1∶4 096. In the great gerbils with the second exposure to Y.pestis, positive antibodies were detected on the 3rd day with the positive rate being 2/9; and the highest antibody titer with 1∶2 048 was noted on the 90th day. Unary linear regression equation of declined F1 antibody of great gerbils was y=0.045x- 0.321 (F=115.40, P< 0.001), and the shortest duration for F1-antibody titer declining from 1∶4 096 to 0 was 140 d and the longest duration 200 d.@*Conclusion@#Great gerbils infected with the high concentration of Y. pestis fluid show shorter duration in producing F1-antibody, the antibody positive rate is also higher, and the highest antibody titer can reach 1∶4 096. The great gerbils could hold the plague F1 antibodies for a long time which was about 140 to 200 days from the highest titer.
ABSTRACT
We investigated the current situation about free-ranging dogs infection with plague and provided relevant data for plague prevention and control in Karamay City.We examined the dog serum F1 antibody by indirect hemagglutination assay (IHA).Results showed that the F1 antibody was found in 1 of 13 dogs serum samples,and the positive rate was 7.69％.The free-ranging dogs plays an important role in controlling animal plague epidemic,and there are potential risk for local people's infection of plague.
ABSTRACT
Objective To observe the dynamics of F1 antibody and immunoglobulin M (IgM) in cats after vaccinated Yersinia pestis,to discuss the significance of detection of F1 antibody and IgM in surveillance of animal plague.Methods The 3 cats were vaccinated Yersinia pestis on their backs with muhipoint hypodermic injection and blood samples were collected via femoral vein on 3rd to 521st days after injection.F1 antibody was detected by sandwich Enzyme-linked immunosorbent assay (ELISA),and IgM of F1 antibody was determined with a capture antibody.Results After vaccinated Yersinia pestis for 3rd days,F1 antibody and IgM appeared slightly positive,with the titer of 1 ∶ 22.00 and 1 ∶ 20.33,respectively.The titer of F1 antibody increased to 1 ∶ 25.33 on the 4th day,and reached the peak of 1 ∶ 29.67 on the 97th day,kept 1 ∶ 25.33 on the 521st day.While the titer of IgM reached peak of 1 ∶ 212.00 on the 7th to 10th days,and decreased rapidly to below the positive standard on the 30th day.Conclusions Detection of F1 antibody in cats with plague by sandwich ELISA can trace plague prevalence in animals back to a long time,which may be applied for investigation of plague foci.A single serum sample can determine early animal plague with a capture antibody to detect IgM of F1 antibody in cat with the plague,and a single serum sample tested with the two methods at the same time for detection of F1 antibody and IgM can precisely verify the infection time of plague in animals for 3 to 7 days.
ABSTRACT
Objective To analyse the feasibility of detecting F1 antibody to Yersinia pestis in flushing fluid of heart blood of Rhombomys opimus with enzyme linked immunosorbent assay(ELISA) method and its application value in surveillance of the disease. Methods Serum, flushing fluid of heart blood and infusion fluid of liver and spleen of Rhombomys opimus, which were caught by capture in the plague focus of Zunger basin in 2007, were taken to carry out detection for F1 antibodies to Yersinia pestis with ELISA method. The data were processed with SPSS 17.0. Results Positive rate and average titer of serum were 12.35%(11/162) and 25.35, of flushing fluid of heart blood were 10.49%(17/162) and 23.75 and of the infusion fluid of liver and spleen 6.79%(17/162) and 2240,respectively. No statistical difference was found in positive detection rate when it was compared between serum and flushing fluid of heart blood(χ2 = 1.333, P ＞ 0.05), but it was obviously different between serum and infusion fluid of liver and spleen(χ2 = 7.111, P ＜ 0.01 ) and between flushing fluid of heart blood and infusion fluid of liver and spleen(x2 = 6.250, P ＜ 0.05). There was a significant difference in average titer between serum, flushing fluid of heart blood and infusion fluid of liver and spleen(t = 2.290, 3.612, P ＜ 0.05 or ＜ 0.01 ). The plague F1 antibody positive coincidence rate of serum and flushing fluid of heart blood was 85.0%(17/20), of serum and infusion fluid of liver and spleen was 55.0% (11/20), and of flushing fluid of heart blood and infusion fluid of liver and spleen was 64.7%(11/17). Conclusions The ELISA method can detect Fl antibody in flushing fluid of heart blood,and the method is feasible in plague surveillance.