Identification of an IS711 element interrupting the wboA gene of Brucella abortus vaccine strain RB51 and a PCR assay to distinguish strain RB51 fromother Brucella species and strains

Brucella abortus vaccine strain RB51 is a natural stable attenuated rough m utant derived from the virulent strain 2308. The genetic mutations that are responsible for the roughness and the attenuation of strain RB51 have not been identified until now. Also, except for an assay based on pulsed-field gel electrophoresis, no other simple method to differentiate strain RB51 fr om its parent strain 2308 is available. In the present study, we demonstrat e that the wboA gene encoding a glycosyltransferase, an enzyme essential fo r the synthesis of O antigen, is disrupted by an IS711 element in B. abortu s vaccine strain RB51. Exploiting this feature, we developed a PCR assay th at distinguishes strain RB51 from all other Brucella species and strains te sted.