Single-tube duplex-PCR for specific detection and differentiation of Brucella abortus S19 vaccine strain from other Brucella spp

A simple single-tube duplex-PCR assay was optimized for rapid and sensitive detection and differentiation of Brucella abortus (B.abortus) S19 vaccine strain from other Brucella spp.(B.abortus 544,B abortus S99,B.melitensis 16M,B.suis).This assay was optimized using two primer pairs that were designed, one targeting genus specific multicopy IS711 and another eryC for the development of the duplex-PCR assay. Specificity of the assay was assessed using DNA templates from various Brucella species (B.abortus, B.melitensis, B.suis) and non Brucella bacteria like Staphylococcus aureus, Proteus vulgaris, Pasteurella multocida, Pseudomonas aeruginosa, Citrobacter freundii, E. coli, Salmonella enteritidis, Campylobacter jejuni and Listeria monocytogenes. The assay was also evaluated on spiked milk samples with known B.abortus cultures. The assay was able to detect up to 2.47 x 10(3)CFU of B. abortus S99 organism in spiked milk sample. The assay was further validated in 53 clinical specimens (aborted foetal stomach content). Results confirm that Single tube duplex-PCR assay was useful for early and rapid detection and differentiation of B. abortus vaccine strain S19 from other Brucella spp in milk as well as in clinical specimen.