Primer target sites in Omp2 locus
The Omp2 locus in all species except B. ovis is composed of two closely related genes, Omp2b and Omp2a. These are oriented in opposite transcriptional directions (8). A, B, and C represent the Omp2 maps reported for B. abortus (Bv. 1), B. melitensis (Bv. 1), and B. neotomae, respectively (9). The arrows indicate primer annealing sites and the bars represent the amplified fragment sizes. The 720-bp fragment changes in length to 900 bp for strains other than B. abortus (Bv. 1), whereas in B. ovis(a) the 600-bp fragment is not produced as it lacks the Omp2b and in B. canis(b) the 200-pb fragment is absent. In B. neotomae, the 2a900 primer amplifies both genes. The KpnI restriction site (black dot) is present in the 900-bp fragment from Omp2b.