Expression and Immunogenicity of VP40 Protein of ZEBOV

EBOV outbreaks continue to threaten the world due to the absence of effective vaccines and therapeutics. Easy-to-use and rapid diagnostic tests for EBOV are highly desired for prevention and control of the EVD epidemic.
Escherichia coli expression system was used to express VP40 protein of Zaire Ebola virus (ZEBOV) as water-soluble protein upon optimization of temperature, time, and IPTG concentration. VP40 protein was purified through Ni-NTA affinity chromatography and applied to immunize rabbits for immunogenicity analysis. Rabbit polyclonal antibodies against VP40 protein was produced and antibody response was analyzed using Western blot, enzyme-linked immunosorbent assay (ELISA), and immunoperoxidase monolayer assay (IPMA).
Recombinant full-length VP40 protein of ZEBOV was expressed in E. coli Rosetta (DE3) cells as water-soluble protein. Analysis of antibody responses showed that rabbit polyclonal antibodies against VP40 protein could react specifically with this E. coli-expressed protein in Western blot and ELISA, and antibody titers in ELISA reached 1:125600. Besides, the produced rabbit polyclonal antibodies bound to VP40 proteins eukaryotically expressed by transfecting pcDNA-eGFP-VP40 into BHK-21 cells in IPMA.
These results show that the prokaryotically expressed VP40 protein has high immunogenicity and can be used as diagnostic antigen in ELISA and other immunoassays. The strategy used in this study might be a potential way for preparing diagnostic agents for prevention and control of exotic diseases.