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Open Access Highly Accessed Research article

MLVA genotyping of Chinese human Brucella melitensis biovar 1, 2 and 3 isolates

Hai Jiang1, Mengguang Fan2, Jingdiao Chen3, Jingchuan Mi2, Ruiping Yu2, Hongyan Zhao1, Dongri Piao1, Changwen Ke3, Xiaoling Deng3, Guozhong Tian1 and Buyun Cui1*

Author Affiliations

1 State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 155 Changbai Road, Changping, Beijing 102206, PR China

2 Department of Brucellosis, Inner Mongolia Center of Endemic Disease Control and Research, 50 Erdos Street, Huhhot 010031, PR China

3 Department of Bacterial Pathogens, Institute for Pathogenic Microorganisms, Guangdong Center for Disease Control and Prevention, 176 Newport Road West, Guangzhou 510300, PR China

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BMC Microbiology 2011, 11:256  doi:10.1186/1471-2180-11-256

Published: 22 November 2011

Abstract

Background

Since 1950, Brucella melitensis has been the predominant strain associated with human brucellosis in China. In this study we investigated the genotypic characteristics of B. melitensis isolates from China using a multiple-locus variable-number tandem-repeat analysis (MLVA) and evaluated the utility of MLVA with regards to epidemiological trace-back investigation.

Results

A total of 105 B. melitensis strains isolated from throughout China were divided into 69 MLVA types using MLVA-16. Nei's genetic diversity indices for the various loci ranged between 0.00 - 0.84. 12 out 16 loci were the low diversity with values < 0.2 and the most discriminatory markers were bruce16 and bruce30 with a diversity index of > 0.75 and containing 8 and 7 alleles, respectively. Many isolates were single-locus or double-locus variants of closely related B. melitensis isolates from different regions, including the north and south of China. Using panel 1, the majority of strains (84/105) were genotype 42 clustering to the 'East Mediterranean' B. melitensis group. Chinese B. melitensis are classified in limited number of closely related genotypes showing variation mainly at the panel 2B loci.

Conclusion

The MLVA-16 assay can be useful to reveal the predominant genotypes and strain relatedness in endemic or non-endemic regions of brucellosis. However it is not suitable for biovar differentiation of B. melitensis. Genotype 42 is widely distributed throughout China during a long time. Bruce 16 and bruce 30 in panel 2B markers are most useful for typing Chinese isolates.