Brucellosis 2003 proceedings - PHIDIAS

Poster Session
contrary, all Rifr strains carried one or two missense mutations within the rpoB gene
resulting in eight different genotypes. The most frequently rpoB mutations affected
either Asp-536 or Val-154 and Met-1249. Our results represent the first study to
detect specific rpoB mutations and evaluate their correlation to resistance phenotype
in Brucella spp.
114- EVIDENCE OF IS711 TRANSPOSITION IN B. ovis AND B. maris.
Alain Ocampo Sosa and Juan M. García-Lobo. Laboratorio de Microbiología. Departamento de
Biología Molecular. Universidad de Cantabria. Spain.
Brucella genome was shown to harbour an IS element denominated IS711 or
IS6501. IS711 is specific of Brucella and it is found in the genomes of all the different
species in a variable copy number ranging from 7 copies in B. abortus, B. melitensis
and B. suis to about 30 in B. ovis and those species isolated from marine mammals
(named B. maris) There was no evidence of transposition of IS711 so far, but the fact
of that it has recently been reported a copy of IS711 interrupting the wboA in B.
abortus strain RB51, not present in the rest of species and biovars, and the large
copy number of this element in B. ovis and B. maris isolates, lead to think that IS711
can still transpose.
In this study we report an evidence of IS711 transposition from B. ovis and B.
maris by using a “transposon trap” plasmid pGBG1 for isolating mobile DNA
elements. The selection module that contains the mutagenesis target is composed of
a silent tetA gene controlled by the pR promoter of bacteriophage l, which is
repressed by the l CI repressor in which mutations produce a tetracycline resistance
phenotype. Brucella melitensis 16M, B. abortus RB51, B. ovis BOC22 (field strain)
and B. maris strains (B14/94, B1/94,B2/94) containing pGBG1 were grown in specific
culture media with tetracycline (Tc) till the appearance of Tc resistant mutants (TcR).
Then the TcR colonies were analysed by PCR with specific primers from the target
sequence to detect the presence of transpositional mutations. TcR mutants due to
IS711 transposition events were only detected in B. ovis and B. maris strains, for the
rest of Brucella strains tested were only found TcR mutants due to point mutations
and nucleotide deletions Five different copies of IS711 were found to transpose to
the repressor.
115- PHYLOGENETIC ANALYSIS OF THE GENUS Brucella WITH PARTICULAR
REFERENCE TO MARINE MAMMAL ISOLATES.
M. Stubberfield 1 , J.Bashiruddin 1 , C. Dawson 1 , A. Whatmore 1 , G. Foster 2 , D. Ewalt 3 , A. MacMillan 1 . (1)
Department of Statutory and Exotic Bacterial Diseases, Veterinary Laboratories Agency, Surrey, UK.
(2) Scottish Agricultural College, Veterinary Science Division, Inverness, UK. (3) USDA, Ames, Iowa,
U.S.A.
Brucella strains have been isolated from marine mammal species since the
mid 1990’s and have subsequently been typed by classical and molecular methods.
Typing approaches indicate that marine strains are clearly different from the
terrestrial strains and PCR-RFLP of the omp2 loci (Microbiol. 1998, 144, 3267-3273)
IS711 fingerprinting (J. Clin. Microbiol. 2000, 38, 1258-1262), and AFLP analysis also
indicate that there are differences between the marine strains. To resolve these
Brucellosis 2003 International Research Conference
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