Abstract

PAVAN, M. E.  and  CAIRO, F.. Molecular study of Argentine strains of Bacillus anthracis. Rev. argent. microbiol. [online]. 2007, vol.39, n.2, pp.77-80. ISSN 0325-7541.

Bacillus anthracis is one of the most monomorphic bacteria known and epidemiological studies of this microorganism have been hampered by the lack of molecular markers. For the genotyping of fourteen Argentine field strains and the vaccine strain Sterne 34F₂, the presence or absence of the virulence plasmids as well as _vrrA locus containing a variable-number tandem repeat (VNTR) and presenting a polymorphism involving five variants, were analyzed. Strains were isolated from cows, sheep and pigs during outbreaks occurred in Buenos Aires, Entre Ríos, Santa Fe and La Pampa in the past fifty years. All of the field strains presented plasmids pXO1 and pXO2, except for a strain isolated from pig that only presented plasmid pXO2. All the strains and the vaccine strain belonged to the same VNTR variant that was defined by sequencing the vrrA locus from three of the isolates and the strain 34F₂. These sequences were completely identical and corresponded to the variant VNTR₄. Thus, the fourteen Argentine B. anthracis strains studied showed great uniformity at molecular level even though they had been isolated from different mammal species within a wide time period and covering an extensive geographical area.

Keywords : Bacillus anthracis; Typing; Variable-number tandem repeat; VNTR; vrrA gene; PCR.

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