The present invention relates to an isolated antigenic polypeptide for use in detecting or preventing melioidosis, encoded by a truncated polynucleotide fragment having a nucleotide sequence as set forth in SEQ ID NO: 1 or the complementary sequence thereof. The present invention also relates to a recombinant plasmid comprising a cloning vector and the truncated polynucleotide; and a transformant harbouring a recombinant plasmid comprising the truncated polynucleotide fragment, wherein the recombinant plasmid being expressible in a bacterial host to yield a truncated antigenic polypeptide. The truncated protein is confirmed antigenic since it can be recognised by melioidosis patients’ serum. The most illustrative drawing