African Lineage Brucella melitensis Isolates from Omani Livestock

Abstract

Brucellosis is a common livestock disease in the Middle East and North Africa, but remains poorly described in the region both genetically and epidemiologically. Traditionally found in goats and sheep, Brucella melitensis is increasingly recognized as infecting camels. Most studies of brucellosis in camels to date have focused on serological surveys, providing only limited understanding of the molecular epidemiology of circulating strains. We genotyped B. melitensis isolates from Omani camels using whole genome SNP assays and VNTRs to provide context for regional brucellosis cases. We identified a lineage of B. melitensis circulating in camels as well as in goats, sheep, and cattle in Oman. This lineage is genetically distinct from most genotypes from the Arabian Peninsula and from isolates from much of the rest of the Middle East. We then developed diagnostic assays that rapidly identify strains from this lineage. In analyses of genotypes from throughout the region, Omani isolates were genetically most closely related to strains from brucellosis cases in humans and livestock in North Africa. Our findings suggest an African origin for B. melitensis in Oman that has likely occurred through the trade of infected livestock. Moreover, African lineages of B. melitensis appear to be undersampled and consequently are underrepresented in genetic databases for Brucella. As we begin to more fully understand global genomic diversity of B. melitensis, finding and characterizing these unique but widespread lineages is essential. We predict that increased sampling of humans and livestock in Africa will reveal little known diversity in this important zoonotic pathogen.

Persistence of Brucella abortus lineages revealed by genomic characterization and phylodynamic analysis

“…In this study, the MLVA-16 results obtained did not match those obtained by phylogeny based on WGS. This difference may be explained by the higher resolution power provided by WGS and homoplasy of B. abortus VNTR markers, as previously proposed [55][56][57][58].…”

Serological and Molecular Detection of Bovine Brucellosis at Institutional Livestock Farms in Punjab, Pakistan

“…The sera were then subjected to DNA extraction by Blood Genomic DNA Extraction Mini Kit (Favorgen ® , Ping-Tung, Taiwan) followed by detection/differentiation of Brucellae at species level by real-time PCR using SYBR ® Green as described earlier by using previously described sets of primers [26,27]. Each DNA extraction procedure was run along with E. coli negative controls and B. abortus (Veterinary Research Institute, Lahore, Pakistan) and B. melitensis (University of Agriculture, Faisalabad, Pakistan) [6] were used as positive controls in PCR procedure. As no reports on B. suis were available in the country, we considered B. suis was not prevalent in the area, hence no controls were used.…”

“…They are non-spore forming, non-motile, non-hemolytic and facultative intra-cellular living, Gram-negative coccobacilli. Although Brucellae show a certain host preference, e.g., B. abortus prefers bovines and B. melitensis small ruminants, cross-species transmission does occur when different animals are in close contact with each other [1][2][3][4][5][6]. Brucellosis occurs worldwide, especially in developing and tropical countries, whereas North and Central Europe, Australia, New Zealand, Japan, and Canada are considered as being free from conventional brucellosis in domestic animals [7].…”

Brucella Genomics: Macro and Micro Evolution

“…To reduce homoplasy and to understand phylogenetic relationships deeper, a systematic approach in Brucella MLVA, is to use the most stable VNTRs or provide further weight to the markers [ 133 ]. However, this could limit the evidence of more recent epidemiological connections [ 134 ]. Species like B. melitensis and B. ceti have proven a fair comparison of MLVA-16 cladograms and WGS phylogenetic reconstruction in the global context [ 27 , 135 ].…”