Virulence associated proteins of Brucella abortus identified by paired two-dimensional gel electrophoretic comparisons of virulent, vaccine and LPS deficient strains.

To identify molecular determinants of virulence, the proteins of Brucella abortus strains 2308 (virulent), S19 (vaccine) and lipopolysaccharide deficient rough mutants derived from each (RB51 and S19M3 respectively) were compared by 2-D gel electrophoresis. A total of 996 proteins were identified on autoradiographs of 2-D gels containing [35S]-labeled proteins from these four strains. Proteins differing qualitatively or quantitatively (greater than or equal to 10X) between 2308 and S19 are implicated in virulence and are identified by Mr and pI. Paired comparisons of proteins present in both 2308 and RB51 and missing in both S19 and M3 were used to make tentative identification of 14 putative virulence proteins representing primary expression of genetic differences between virulent and vaccine strains. 28 proteins and/or core lipopolysaccharide-protein complexes involved in the biosynthesis of lipopolysaccharide were identified by paired comparisons of proteins present in both smooth strains and missing in both rough strains.