Cloning and prokaryotic expression of the gene encoding outer membrane protein 31 (OMP31) of Brucella abortus.

The full-length outer membrane protein gene OMP31 of Brucella abortus was amplified by PCR from the aborted grime collected from one cattle farm in Hebei Province and successfully cloned into pMD18-T vector.Sequence analyses showed that the complete open reading frame with an ATG initiation codon comprised 723 nucleotides and encoded a protein of 241 amino acids.The OMP31 gene was sub-cloned into expression vector pET-28a(+) and the recombinant plasmid was then transformed into competent Rossetta(DE3) bacteria.SDS-PAGE and Western-blot analyses revealed that the recombinant protein OMP31 with a molecular weight of 28ku was highly expressed in the host cells by the IPTG induction and could be identified by specific antisera against Brucella.