Cloning and nucleotide sequence analysis of a Brucella abortus gene encoding an 18 kDa immunoreactive protein

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A DNA fragment encoding an ~18 kDa protein from Brucella abortus strain 2308 was cloned and expressed in Escherichia coli. This recombinant protein, designated BA18K, reacted in Western blot analysis with sera obtained from experimentally and naturally infected animals including mice, goats, dogs and humans. Restriction enzyme analysis of the plasmid (pBA28) encoding BA18K revealed the presence of an ~8.7 kbp Sau3A genomic DNA fragment within the vector and subsequent subcloning and Western blot analysis limited the region encoding BA18K to an ~3.0 kbp Pst I DNA fragment. DNA sequence analysis of this region identified an open reading frame capable of encoding a protein of 177 amino acids with a predicted relative molecular mass of 17,529. Comparison of the deduced amino acid sequence of BA18K with those in the protein sequence databases yielded no homology with previously described proteins from other bacterial genera. These searches did, however, indicate that BA18K is identical to the previously described outer membrane protein (OMP) from B. abortus strain 544 designated Omp19.

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Microbial Pathogenesis

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