Prokaryotic Expression and Immunological Analysis of the Flagella Gene of Edwardsiella tarda

Edwardsiella tarda strain ETY was isolated from Japanese eel. With two pairs of specific primers, the flagella gene(ETF) was amplified from the strain ETY via nest-PCR. After sequencing analysis, the nucleotide data had been further analyzed by DNAman and ClutalW software. The analysis results showed that ETF had a longest open reading frame (ORF) of 1 257 bp, which was predicted to encode a 419-aa protein with the molecular weight of 43.951 kD. Considering ELISA (enzyme-linked immunosorbent assay) analysis and Western-blotting analysis, it was proved that the expressed gene products shared similar antigenicity and immunocompetence with the natural flagella. The protective rate in the Japanese eel immunized with the ETF-TrxA fusion protein and ISA adjuvant is 100%. It is the first time that the ETF gene was efficient expressed in E.coli., and it also primarily studied the ETF function of Edwardsiella tarda in invasion and inducing immunoreaction. The results enable the development and formulation of an appropriate and effective subunit vaccine(s) against Japanese eel edwardsiellosis.