Development of a multiplex polymerase chain reaction assay for differentiation of field strain isolates and vaccine strains S19 and RB51 of Brucella in Iran

Bovine brucellosis is a zoonotic disease distributed worldwide and characterized by abortion and reducedfertility in cows. Since brucellosis eradication programme in Iran uses vaccination, test, slaughter andquarantine as control measures, it is essential to distinguish vaccine strains from strains that cause infectionsamong vaccinated cattle herds. We developed and evaluated a multiplex polymerase chain reaction (PCR)assay to identify and differentiate the vaccine strains from wild field isolates, including all Brucella typesusually found in cattle in Iran. Two pair primers were used to amplify eri and wbo regions of DNA sequencesthose strain-specific targets for B. abortus S19 and RB51 vaccine strains. This multiplex PCR methodevaluated with DNA from reference strains, two vaccine strains and 29 field strains of Brucella. The resultsshowed that the multiplex PCR can differentiate Brucella isolates into three categories: strain 19 (S19), strainRB51 and field strains. This PCR assay was successfully used, compared with traditional method todifferentiate of S19 and RB51 from field Brucella isolates