EFFECT OF P39 GENE DELETION IN LIVE BRUCELLA VACCINE STRAINS ON RESIDUAL VIRULENCE AND PROTECTIVE ACTIVITY IN MICE

The 39-kilodalton protein (P39) has previously been shown to be an imm unodominant protein in Brucella infections. P39 gene deletion mutants of vaccine strains Brucella abortus S19 and Brucella melitensis Rev.1 were constructed by gene replacement. This deletion did not significan tly modify the residual virulence of both vaccine strains in CD-1 mice . CD-1 mice vaccinated with the parent or mutant strains were protecte d against a virulent challenge. Mutant vaccine strains devoid of P39 c ould provide a means for differentiating vaccinated from infected anim als.