Several PCR assays which identify the genus BruceUla but do not discriminate among species have been reported. We describe a PCR assay that comprises five oligonucleotide primers which can identify selected biovars of four species of Brucella. Individual biovars within a species are not differentiated. The assay can identify three biovars (1, 2, and 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 Bruceila species typically isolated from cattle in the United States, a goal of the present research. The assay exploits the polymorphism arising from species-specific localization of the genetic element IS711 in the Brucella chromosome. Identity is determined by the size(s) of the product(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 described method, there was 100% agreement with the identifications made by conventional methods. Six closely related bacteria (Agrobacterium radiobacter, Agrobacterium rhizogenes, Ochrobactrum anthropi, Rhizobium leguminosarum, Rhizobium meliloti, and Rhzodospirillum rubrum) and two control bacteria (Bordeteila bronchiseptica and Escherichia coli) tested negative by the assay.

Brucellosis is a worldwide disease of humans and livestock that is caused by a number of very closely related classical Brucella species in the alpha-2 subdivision of the Proteobacteria. We report the complete genome sequence of Brucella abortus field isolate 9-941 and compare it to those of Brucella suis 1330 and Brucella melitensis 16 M. The genomes of these Brucella species are strikingly similar, with nearly identical genetic content and gene organization. However, a number of insertion-deletion events and several polymorphic regions encoding putative outer membrane proteins were identified among the genomes. Several fragments previously identified as unique to either B. suis or B. melitensis were present in the B. abortus genome. Even though several fragments were shared between only B. abortus and B. suis, B. abortus shared more fragments and had fewer nucleotide polymorphisms with B. melitensis than B. suis. The complete genomic sequence of B. abortus provides an important resource for further investigations into determinants of the pathogenicity and virulence phenotypes of these bacteria.Brucellosis is a bacterial disease of animals that can be transmitted to humans. The primary impact of brucellosis stems from losses due to reproductive failure in food animals and the loss of human productivity. Since brucellosis threatens the food supply and causes undulant fever, a long, debilitating disease in humans, Brucella species are recognized as potential agricultural, civilian, and military bioterrorism agents. Brucellosis in food animals is controlled by vaccination. Human brucellosis is treatable with antibiotics, though the course of antibiotic treatment must be prolonged due to the intracellular nature of Brucella.Analysis of 16S rRNA sequences places Brucella spp. as members of the alpha-2 Proteobacteria (31). The genus Brucella has six recognized species, all of which exhibit distinct host preferences (25,26). The high degree of similarity among the brucellae (1, 3, 13, 33) lends support to the proposal that the classical species of Brucella are actually strains of Brucella melitensis (40). However, this view conflicts with the hypothesized evolutionary isolation of these classical species due to their intracellular existence and host preference (29). Common host-pathogen associations among the classical Brucella species are as follows: B.