Genetic Polymorphism Characteristics of Brucella canis Isolated in China

Dongdong Di,Xiaojun Zhang,Jingli Kang,Hai Jiang,Lin Zhu,Hongyan Zhao,Zhuo Zhao,Lili Tian,Wenqing Yao,Pingyuan Guan,Lingling Mao,Heng Wang,Xiang Mao,Pengfei Du,Guozhong Tian,Weixing Fan,Buyun Cui,Dongri Piao,Roy Martin Roop

doi:10.1371/journal.pone.0084862

Abstract

In China, brucellosis is an endemic disease typically caused by Brucella melitensis infection (biovars 1 and 3). Brucella canis infection in dogs has not traditionally recognized as a major problem. In recent years however, brucellosis resulting from Brucella canis infection has also been reported, suggesting that infections from this species may be increasing. Data concerning the epidemiology of brucellosis resulting from Brucella canis infection is limited. Therefore, the purpose of this study was to assess the diversity among Chinese Brucella canis strains for epidemiological purposes. First, we employed a 16-marker VNTR assay (Brucella MLVA-16) to assess the diversity and epidemiological relationship of 29 Brucella canis isolates from diverse locations throughout China with 38 isolates from other countries. MLVA-16 analysis separated the 67 Brucella canis isolates into 57 genotypes that grouped into five clusters with genetic similarity coefficients ranging from 67.73 to 100%. Moreover, this analysis revealed a new genotype (2-3-9-11-3-1-5-1:118), which was present in two isolates recovered from Guangxi in 1986 and 1987. Second, multiplex PCR and sequencing analysis were used to determine whether the 29 Chinese Brucella canis isolates had the characteristic BMEI1435 gene deletion. Only two isolates had this deletion. Third, amplification of the omp25 gene revealed that 26 isolates from China had a T545C mutation. Collectively, this study reveals that considerable diversity exists among Brucella canis isolates in China and provides resources for studying the genetic variation and microevolution of Brucella.

Highlights

Brucellosis, caused by various species of the Gram-negative bacterium Brucella, continues to be one of the most serious zoonotic diseases for humans and animals throughout the world [1]
B. canis infection has not been the major cause of brucellosis in China [7,8,9,10], recent outbreaks in Beijing and other provinces suggest that this infection may be on the rise [8]
A substantial proportion of B. canis isolates cannot be correctly identified using this approach. We present both Brucella multi-locus variable-number tandem-repeat analysis (MLVA)-16 and PCR data from Chinese B. canis isolates recovered from brucellosis outbreaks from different geographical origins

Summary

Introduction

Brucellosis, caused by various species of the Gram-negative bacterium Brucella, continues to be one of the most serious zoonotic diseases for humans and animals throughout the world [1]. The number of published reports describing brucellosis resulting from B. canis infection has increased [2,3,4,5,6]. B. canis infection has not been the major cause of brucellosis in China [7,8,9,10], recent outbreaks in Beijing and other provinces suggest that this infection may be on the rise [8]. In order to effectively prevent this disease, it is important to identify what strain of Brucella has caused the infection. Most molecular subtyping tools and ‘‘classical biotyping’’ methods lack sufficient discriminatory power for epidemiological investigations. Effective molecular subtyping tools capable of reproducibly distinguishing differences between strains must be implemented

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Conclusion