[Clone expression of the caf1 gene of Yersinia pestis and immunological evaluation on recombinant F1 antigen].

OBJECTIVE: To get recombinant F1 antigen (rF1) and to construct the detection dipstick of plague antibody. METHODS: The caf1 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 rF1 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 F1 antigen in detecting plague antibody. It seemed that there was a better consistency of 97.9% (kappa = 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.

[Study on the application and evaluation of methods for gene and antigen detection in plague surveillance program].

OBJECTIVE: To apply and evaluate new methods regarding specific gene and antigen detection in plague surveillance program. METHODS: 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. RESULTS: 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%. CONCLUSION: The new standard being used for specific gene and antigen detection could increase the positive rate of diagnosis on plague.