Objective:To construct the prokaryotic expression vector of Cpf1 of Francisella tularensis subsp. Novicida

to express the recombinant protein in E.coli BL21 and purify it to prepare FnCpf1 polyclonal antibody. Methods:FnCpf1 gene was amplified by PCR and subcloned into a prokaryotic expression vector pET-32a（+）. Then the pET-32a（+）-FnCpf1 was transformed into E. coli BL21 and the recombinant FnCpf1 was induced with IPTG. The FnCpf1 protein was purified by the nickel ion chelating beads affinity purification and was used to immunize rabbits. The titer and specificity of the polyclonal antibody was respectively measured by Indirect enzyme-linked immunosorbent assay（ELISA）and Western blot. Results:Restriction and sequencing analysis proved that recombinant plasmid pET32a（+）-FnCpf1 was constructed correctly. SDS-PAGE analysis showed that FnCpf1 with a relative molecular mass of 160 k D was expressed in a soluble form. The purity of the purified protein reached more than 95 percent. ELISA showed the titer of FnCpf1 polyclonal antibody was 1∶512 000 and Western blot test demonstrated that the polyclonal antibody could specifically bind with FnCpf1 recombinant protein. Conclusion:FnCpf1 recombinant protein is successfully expressed in the prokaryotic system and FnCpf1 polyclonal antibody is prepared with high titer and specificity

which would lay the foundation for further study on the biological characteristics of Cpf1.