Distinctive phenotypic and molecular characteristics of Brucella abortus strains isolated from Mongolia

Authors: JI-YEON KIM, SUNG-IL KANG, JANCHIVDORJ ERDENEBAATAAR, BATBAATAR VANAABAATAR, GOMBOSUREN ULZIISAIKHAN, OCHIRBAT KHURSBAATAR, KICHAN LEE, JIN JU LEE, SO-RA SUNG, SUK CHAN JUNG, YONG HO PARK, HAN-SANG YOO, MOON HER

Abstract: Recently, some Brucella abortus were isolated from human and various livestock in Mongolia, and the classical biotyping and molecular detection methods (PCR assays, 16S rRNA sequencing analysis, and multilocus variable number tandem repeat analysis (MLVA)) were applied to investigate them. Of the 16 isolates, nine and seven were confirmed as biovar (bv.) 3 and untyped by the classical biotyping assay, respectively. The phenotypic characteristics of the untyped isolates were consistent with those of the former B. abortus bv. 7, which is not included in the current Brucella taxonomy. Additionally, genus- and species-specific PCR supported that the untyped Mongolian isolates belonged to B. abortus. The untyped isolates were clustered into a peculiar genotype in the results of 16S rRNA sequencing and MLVA patterns using 16 loci. Taken all together, the untyped B. abortus isolates, which are some of the most predominant B. abortus biovars in Mongolia, were estimated to be bv. 7. Moreover, the Mongolian B. abortus isolates were closely associated with Chinese isolates according to MLVA. Therefore, animal quarantine and control measures should be strengthened to prevent the spillover of Brucella species into adjacent countries.

Keywords: Brucella abortus, phenotyping, molecular detection, bv. 3 and 7, Mongolia

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