Application and evaluation of the MLVA typing assay for the Brucella abortus strains isolated in Korea.
BACKGROUND
A Brucella eradication program has been executed in Korea. To effectively prevent and control brucellosis, a molecular method for genetic identification and epidemiological trace-back must be established. As part of that, the MLVA typing assay was evaluated and applied to B. abortus isolates for analyzing the characteristics of the regional distribution and relationships of foreign isolates.


RESULTS
A total of 177 isolates originating from 105 cattle farms for the period 1996 to 2008 were selected as representatives for the nine provinces of South Korea. A dendrogram of strain relatedness was constructed in accordance with the number of tandem repeat units for 17 loci so that it was possible to trace back in the restricted areas. Even in a farm contaminated by one source, however, the Brucella isolates showed an increase or decrease in one TRs copy number at some loci with high DI values. Moreover, those 17 loci was confirmed in stability via in-vitro and in-vivo passage, and found to be sufficiently stable markers that can readily identify the inoculated strain even if minor changes were detected. In the parsimony analysis with foreign Brucella isolates, domestic isolates were clustered distinctively, and located near the Central and Southern American isolates.


CONCLUSIONS
The MLVA assay has enough discrimination power in the Brucella species level and can be utilized as a tool for the epidemiological trace-back of the B. abortus isolates. But it is important to consider that Brucella isolates may be capable of undergoing minor changes at some loci in the course of infection or in accordance with the changes of the host.
OIE Reference Laboratory for Brucellosis & Zoonosis Laboratory, Bacteriology and Parasitology Division, Veterinary Research Department, National Veterinary Research and Quarantine Service, Anyang, Gyeonggi, Republic of Korea. herm@nvrqs.go.kr
Moon
M
Her
Sung-Il
SI
Kang
Dong-Hee
DH
Cho
Yun-Sang
YS
Cho
In-Yeong
IY
Hwang
Young-Ran
YR
Heo
Suk-Chan
SC
Jung
Han-Sang
HS
Yoo
D000818:Animals; D015373:Bacterial Typing Techniques / Q000379:methods*; D002003:Brucella abortus / Q000145:classification / Q000235:genetics*; D002417:Cattle / Q000382:microbiology; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000235:genetics; D014644:Genetic Variation; D005838:Genotype; D056910:Republic of Korea; D020080:Tandem Repeat Sequences
D004269:DNA, Bacterial