Substantial Virulence Genes among Brucella melitensis Field Strains Isolated from Cattle in Egypt

摘要

Background and Objective: The economic losses due to brucellosis as well as its potential public health in human worldwide encourage more researches to find novel pathways for effective control methods of the disease. The objective of this study was to investigate the most prevalent Brucella strains obtained from cattle and their virulence genes. Materials and Methods: Three hundred small-holders cows in Menoufia governorate, Egypt, were screened for brucellosis using rose bengal test (RBT) and confirmed by complement fixation test (CFT). Milk samples and supra-mammary lymph nodes of serologically positive cows were collected for bacteriological isolation and identification. The obtained isolates were genotyped using PCR and their virulence genes ( omp 25, omp 31, man A, man B, vir B and znu A) were screened. Results: The prevalence rate of bovine brucellosis was 15 (5%), 11 (3.6%) and 7 (2.33%) by RBT, CFT and bacteriological examination, respectively. The seven isolates were identified and genotyped as Brucella melitensis biotype3. Furthermore, the molecular detection of substantial virulence genes revealed that man A, man B, omp 25 and omp 31 genes were detected in all tested B. melitensis strains. Meanwhile, the vir B genes were detected in 4 strains and the znu A genes were detected in 3 strains among the isolated B. melitensis strains. Conclusion: It was concluded that B. melitensis biotype3 was the pre-dominant Brucella spp . as well as omp25, omp 31, man A and man B were the most common related-virulence genes which assumed to play a worthy function in the pathogenesis of brucellosis.