CLONING AND NUCLEOTIDE-SEQUENCE ANALYSIS OF A BRUCELLA-ABORTUS GENE ENCODING AN 18 KDA IMMUNOREACTIVE PROTEIN

A DNA fragment encoding an similar to 18 kDa protein from Brucella abo rtus strain 2308 was cloned and expressed in Escherichia coli. This re combinant 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 simila r to 8.7 kbp Sau3A genomic DNA fragment within the vector and subseque nt subcloning and Western blot analysis limited the region encoding BA 18K to an similar to 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 o f 17 529. Comparison of the deduced amino acid sequence of BA18K with those in the protein sequence databases yielded no homology with previ ously described proteins from other bacterial genera. These searches d id, however, indicate that BA18K is identical to the previously descri bed outer membrane protein (OMP) from B. abortus strain 544 designated Omp19. (C) 1997 Academic Press Limited.