ABSTRACT
Objective To get recombinant F1 antigen (rF1) and to construct the detection dipstick of plague antibody. Methods The cafl 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 rFl 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 Fl antigen in detecting plague antibody. It seemed that there was a better consistency of 97.9% (k= 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.
ABSTRACT
Objective To study the doses and methods of F1 antigen(F1Ag) to immune Balb/c mice during the establishment of hybridoma cell strains. Secreting McAbs against F1Ag of Yersinia pestis. Methods Balb/c mice of seven to nine weeks old were randomly divided into six groups. The first four groups were 150, 100, 50 and 25 μg F1Ag inoculated group, having multipoint hypodermic inoculation of F1Ag of 150, 100, 50 and 25 μg followed by multipoint hypodermic inoculation of F1Ag of 100 μg for a second time and then intraperitoneal injection of 100 μg. Next, hypodermically inoculated group received F1Ag of 100 μg for three times in multiple points. Finally, the intraperitoneal injection group was intraperitoneally inoculated with F1Ag of 100 μg for three times. Emulsification liquid of F1Ag + Complete Frednd's adjuvant(CFA) of equivalence was used in the first inoculation, emulsification liquid of F1Ag + Incomplete Frednd's adjuvant(IFA) balanced mix in the second, F1Ag liquid in the third. One week afterwards, tail blood of the mice was collected to test antibody titers of anti-F1Ag by double antigens sandwich enzyme linked immunosorbent assay (DAgS-ELISA) and trace indirect hemagglutination assay(IHA). Results The levels of antibody of anti-F1Ag in 150,100,50 and 25 μg groups had statistics difference (DAgS-ELISA method: G = 12 173.87,13 440.37,15 024.19 and 4466.72, F= 3.11, P< 0.05;IHA: G = 19 972.32,18 089.40,23 170.47 and 4871.08, F = 4.11, P < 0.05). Immune effect of the 3 groups of 150, 100 and 50 μg was almost the same (P> 0.05), and excelled as compared with that in 25 μg group with statistics difference(DAgS-ELISA method: t = 2.18,2.39,2.73, P < 0.05;IHA: t = 2.54,2.73,3.13, P< 0.05). The titer of F1 antibody had an increasing trend from the 100 μg group to hypodermic group and intraperitoneal injection groups, but without statistics difference (DAgS-ELISA method: G = 8933.44, 9986.16, 13 440.37;IHA: G = 13 777.25,16 384.00, 18 089.40, F = 0.66,0.25, all P > 0.05). Conclusions Hyodermical inoculation of F1Ag with the first dose of 50 μg in multiple points for mouse is appropriate, and a strengthening dose of 100 μg in an intraperitoneal injection may shorten the immune period.
ABSTRACT
Objective To develop a new type of gene vaccine against plague. Methods caf1 gene of caf Operon Encoding F1 Antigen of Y. pestis was inserted into pHSS6-mTn-3xHA/lacZ library plasmids, the recombinant plasmids were linearized with Not I and transformed into yeast cell by lithium acetate (LiAc) method to induce homologous recombination. Positive recombinants were then selected with uracil-lack medium. Results These recombinants were confirmed by colony PCR to have the target gene fragments. Conclusion The present study provided a platform for constructing a novel expression system for expressing Y. pestis F1 Antigen via homologous recombination in Saccharomyces cerevisiae, which may contribute to the genetic prevention of plague through digestive-tract-route (DTR).