DETERMINATION OF STABILITY OF BRUCELLA-ABORTUS RB51 BY USE OF GENOMICFINGERPRINT, OXIDATIVE-METABOLISM, AND COLONIAL MORPHOLOGY AND DIFFERENTIATION OF STRAIN RB51 FROM B-ABORTUS ISOLATES FROM BISON AND ELK

Brucella abortus RB51 and isolates from cattle, bison, and elk were ch aracterized by pulsed-field gel electrophoresis and standard technique s for biotyping Brucella species, which included biochemical, morpholo gical, and antigenic techniques, phage susceptibility, and antibiotic resistance. The objectives were to ascertain the stability of RB51 and to differentiate RB51 from other brucellae. Genomic restriction endon uclease patterns produced by pulsed-field gel electrophoresis demonstr ated a unique fingerprint for RB51 relative to other brucellae. Compar isons of the oxidative metabolic profiles of RB51 after time in vivo ( 14 weeks) and in vitro (75 passages) showed no change in characteristi c patterns of oxygen uptake on selected amino acid and carbohydrate su bstrates, Strain RB51 was biotyped as a typical rough B. abortus biova r 1 (not strain 19) after animal passage or a high number of passages in vitro and remained resistant to rifampin or penicillin and suscepti ble to tetracycline, No reactions with A or M antiserum or with a mono clonal antibody to the O antigen of Brucella lipopolysaccharides were detected; however, RB51 agglutinated with R antiserum. The results ind icate that the genomic fingerprint and rough colonial morphology of RB 51 are stable characteristics and can be used to differentiate this va ccine strain from Brucella isolates from cattle, bison, and elk.