Detection of virulence-associated genes in Brucella melitensis biovar 3, the prevalent field strain in different animal species in Egypt

The current study involved detection of three virulence genes ( bvfA , virB , ure ) by PCR in 52 isolates of Brucella melitensis biovar 3, recovered from different animal species (28 sheep, 10 goats, 9 cattle and 5 buffaloes). Of the 52 B. melitensis strains; 48 (92.3%) isolates carried bvfA genes, 51 (98.1%) isolates had virB genes and 50 (96.2%) isolates were positive for ure genes. The distribution of the virulence genes is not affected by crossing the original host barriers of the animal species, as the three virulence factors ( bvfA , virB and ure ) detected in 28 B. melitensis isolates obtained from ovine species in a ratio of 26/28 (92.9%), 27/28 (96.4%) and 28/28 (100%), respectively. While 10 isolates originating from goats revealed a ratio of 10/10 (100%), 10/10 (100%) and 9/10 (90%) to the same order of virulence genes. Nearly, similar results of virulence genes detection were obtained in B. melitensis obtained from bovine (8/9, 9/9 and 8/9) and Buffalos (4/5, 5/5 and 5/5), respectively. The high prevalence of virulence-associated genes among the B. melitensis isolates detected from different animal species in Egypt indicates a potential virulence of this bacterium. Keywords: Brucella melitensis biovar 3, Egypt, PCR, Virulence genes