Molecular cloning and expression of OspC protein of a Chinese Borrelia afzelli FP1 strain and pre-liminary study on the immune protectivity of the rOspC protein / 中华微生物学和免疫学杂志

ABSTRACT

Objective To clone and express the outer surface protein C ( OspC) from a Chinese Borrelia afzelli FP1 strain and to evaluate the immune protectivity of the recombinant OspC protein ( rOspC) . Methods The gene encoding OspC protein of Borrelia afzelli FP1 strain was amplified by polymerase chain reaction (PCR) and then inserted into pET-30a plasmid to construct the recombinant expression plasmid pET-30a-OspC. The transformed E. coli BL21 strains carrying pET-30a-OspC plasmid were induced by IPTG to express OspC protein. The expressed proteins were purified by Ni-IDA resin chromatography and analyzed by SDS-PAGE and Western blot assay. Indirect immunofluorescence assay ( IFA) was performed to detect anti-rOspC protein antibodies in serum samples from rabbits immunized with rOspC protein. In vitro neutral-ization test was performed for evaluation the immune protectivity of rOspC protein. Results The recombi-nant expression plasmid pET-30a-OspC was successfully constructed and highly expressed in E. coli BL21. A strong antigen-antibody reaction between the rOspC protein and polyclonal antibody against Borrelia afzelli FP1 strain was detected by Western blot assay. The titers of IgG in serum samples from rabbits immunized with rOspC protein were significantly elevated. The in vitro neutralization test indicated that 106/ml of Borre-lia afzelli FP1 strains were neutralized by every anti-OspC protein serum sample from the experiment group. Conclusion The rOspC protein showed a strong immune protectivity against Borrelia afzelli, which could be used in the development of polyvalent subunit vaccine against lyme disease.