Evaluation of EryC as Molecular Marker for Differential Identification of Brucella abortus from Vaccine Strain S 19

Background: To prevent the losses caused by brucellosis, development of diagnostic tools for differentiating vaccinated cattle from infected one is priority in the eradication of the disease. The present study was undertaken for differential identification of Brucella abortus from vaccine strain S19 by EryC PCR. Methods: In this study, 1145 clinical samples of unvaccinated cattle and buffaloes (200 blood samples, 710 sera, 190 vaginal swabs, 20 abomasal contents of foetus, 25 foetal tissues) and 146 blood samples of vaccinated animals were collected from dairy farms in and around Mumbai and Pune region. These samples were processed for isolation of Brucella organisms and further characterized by EryC PCR. Result: The EryC PCR yielded the amplicon of 1257 bp in B. abortus 544, B. melitensis Rev1, all field isolates, 67 vaginal swabs, 23 foetal tissue samples, 80 (40%) blood samples of unvaccinated animals and 21 blood samples of vaccinated animals. Only two out of the 146 blood samples from S19 vaccinated animals showed amplicon of 555 bp. The EryC PCR developed during the present study was found useful in differentiating wild type of Brucella strains from B. abortus S19 and also found effective when tried on reference strains and field samples.