Objective To compare the effect of three methods in diagnosis of plague by detecting of Yersina pestis F1 antigen. Methods In natural foci of plague, wild animal samples, such as blood, liver, spleen,and lymphoid tissue were collected, and the three methods of enzyme linked immunosorbent assay (ELISA),reverse indirect hemagglutination assay(RIHA) and gold-immunochromatography assay(GICA) were employed to detect F1 antigen of Yersina pestis. Results Total of 414 infused organ samples of natural death and captured wild animals in natural foci of plague were determined. Positive samples detected by GICA and ELISA were the same,the positive rates were 5.31%(22/414), both positive and negative coincidence rates were consistently 100%. Only 18 samples were positive by retrial in 186 samples with more than 2 holes aggregation by preliminary examination of RIHA, with nonspecific agglutination rate of 40.6% (168/414) and positive rate of 4.35% (18/414). The positive coincidence rate was 81.82% (18/22) between RIHA with GICA and ELISA, and negative coincidence rate was statistically significant(t = 4.379, P ＜ 0.01). Conclusions ELISA, RIHA and GICA can be used for early diagnosis of plague by detecting F1 antigen. The results of RIHA have quantitative significance, with higher non-specific agglutination rate, and heavy workload of re-examination; GICA and ELISA has the same specificity and sensitivity, but the results of GICA is only qualitative. ELISA excluded the defect of RIHA and GICA, and combines the advantages of both methods.

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.

Objective To establish a capture enzyme-linked immunosorbent assay (ELISA) for detection of plague IgM antibody in herding dogs.Methods ELISA plates were coated with serum IgM antibody against dogs and F1 antibody to plague in the serum of herding dogs was detected by a sandwich ELISA.Results A total of 216 serum samples of herding dogs were tested,26 were positive for plague F1 antibody and the positive rate was 12.03％ (26/216); 14 were positive for plague IgM antibody and the positive rate was 6.48％ (14/216); IgM positive accounted for 53.8％(14/26) of all positive samples.Conclusions Serum plague IgM antibody of herding dogs can be used to predict the prevalent time and distribution of recent animal plague in plague foci indirectly,and to provide reference information for timely implementation of control measures.