DIFFERENTIATION OF BRUCELLA-ABORTUS-BV-1, BRUCELLA-ABORTUS-BV-2, AND BRUCELLA-ABORTUS-BV-4, BRUCELLA-MELITENSIS, BRUCELLA-OVIS, AND BRUCELLA-SUIS-BV-1 BY PCR

Several PCR assays which identify the genus Brucella but do not discri minate among species have been reported. We describe a PCR assay that comprises five oligonucleotide primers which can identify selected bio vars of four species of Brucella. Individual biovars within a species are not differentiated. The assay can identify three biovars (1, 2, an d 4) of B. abortus, all three biovars of B. melitensis, biovar 1 of B. suis, and all B. ovis biovars. These biovars include all of the Bruce lla species typically isolated from cattle in the United States, a goa l of the present research. The assay exploits the polymorphism arising from species-specific localization of the genetic element IS711 in th e Brucella chromosome. Identity is determined by the size(s) of the pr oduct(s) amplified from primers hybridizing at various distances from the element. The performance of the assay with U.S. field isolates was highly effective. When 107 field isolates were screened by the descri bed method, there was 100% agreement with the identifications made by conventional methods. Six closely related bacteria (Agrobacterium radi obacter, Agrobacterium rhizogenes, Ochrobactrum anthropi, Rhizobium le guminosarum, Rhizobium meliloti, and Rhodospirillum rubrum) and two co ntrol bacteria (Bordetella bronchiseptica and Escherichia coli) tested negative by the assay.