For the Brucella species, Hoof-prints, a MLVA assay based on an eight-base pair tandem repeat sequence at eight loci, was introduced as a molecular method for fingerprinting the Brucella isolates . Hoof-prints
were not appropriate for the discrimination of the B. abortus isolates in Korea because of their hypervariability, especially the Hoof 1 and 7 loci, and they need to be replaced by other stable markers [23, 35, 36] The MLVA typing assay, designated to some selections of the MLVA loci, was reported to have a good species identification capability and a higher discriminatory power, and could thus be proposed as a complement of, or even as a substitute for, the classical biotyping methods [23, 27, 30]. This assay showed that it could discriminate isolates originating from BVD-523 chemical structure restricted ABT-888 datasheet geographic sources, indicating its potential as an epidemiological tool [25–27]. Genetic diversity of the Brucella isolates must be investigated, and the epidemiological trace-back tool must be evaluated, for the effective prevention of brucellosis. Thus, we endeavoured to assess the MLVA typing assay of the B. abortus strains isolated in Korea based on 17 primer sets, which were consisted of 16 markers described previously [23, 30] and Hoof 3 used by hoof-prints . Hoof 3 was able to differentiate the B. abortus RB51 vaccine strain (TRs copy number:
4) from its mother strain, B. abortus 2308 (TRs copy number: 5), and was shown to have the discrimnation power of a moderate stable marker (Table 1). As it caused abortion in pregnant cattle, Brucella RB51 vaccination was suspended in Korea in 1997. In late 1999, PFKL however, one B. abortus strain isolated from dairy cattle
was identified as the RB51 vaccine strain using the classical biotyping scheme and differential AMOS PCR [17, 37], and its strain was confirmed to completely coincide with the original strain by 17 loci, especially Hoof 3 (Figure 2). This result shows that Hoof 3 can be increased the discrimination capacity and trace-back ability of the MLVA assay. The 177 strains isolated from 105 cattle farms in nine provinces in Korea from 1996 to 2008 were investigated in this study [see additional file 1]. Bruce 43 appeared to have a variety of alleles, and its DI value was the highest at 0.529 (Table 1). In addition, the B. abortus isolates that originated from the same farms at the same time were sometimes found to have a difference of one copy number for mainly Bruce 30 or 43 (Table 2). Le Fleche et al.  divided the 15 loci into two groups, one consisting of eight loci with a good species identification capability (panel 1) and another complementary group of seven loci with a high discriminatory power (panel 2). Bruce 43 was included in panel 1 and was reported to be a moderately variable marker. Moreover, Al Dahouk et al.  reported that Bruce 43 had three alleles and a 0.