Abstract: Brucella  species is responsible for brucellosis in human and animals, which is still of public health, veterinarian, and economic concern in many regions of the world. Here, a novel molecular diagnosis assay, termed loop-mediated isothermal amplification coupled with nanoparticles-based lateral flow biosensor (LAMP-LFB), was developed and validated for simply, rapidly, and reliably detecting all Brucella  spp. strains. A set of six primers was designed based on the Brucella -specific gene Bscp31 . The Brucella -LAMP results were visually reported by biosensor within 2 mins. A variety of bacterial strains representing several Brucella  species, as well as several Gram-negative and Gram-positive bacterial species were used to determine the analytical sensitivity and specificity of the assay. Optimal LAMP conditions were 63°C for 40 mins, and the assay’s sensitivity was found to be 100 fg of genomic DNA in the pure cultures. No cross-reactions to non-Brucella  strains were obtained; thus, analytical specificity of LAMP-LFB assay is of 100%. Using the protocol, 20 mins for rapid DNA preparation followed by isothermal amplification (40 mins) combined with biosensor detection (2 mins) resulted in a total assay time of approximately 65 mins. In the case of 117 whole blood samples, 13 (11.11%) samples were Brucella -positive by LAMP-LFB, and the diagnostic accuracy was 100% when compared to the culture-biotechnical method. In conclusion, Brucella -LAMP-LFB technique developed in this study is a sensitive and specific method to rapidly identify all Brucella  spp. strains, and can be applied as a potential diagnostic tool for brucellosis in basic, clinical, and field laboratories.
Keywords: Brucella  spp., brucellosis, loop-mediated isothermal amplification, lateral flow biosensor, limit of detection