Multi-locus variable-number tandem repeat analysis of Chinese Brucella strains isolated from 1953 to 2013

Abstract

BackgroundBrucellosis was a common human and livestock disease caused by Brucella strains, the category B priority pathogens by the US Center for Disease Control (CDC). Identified as a priority disease in human and livestock populations, the increasing incidence in recent years in China needs urgent control measures for this disease but the molecular background important for monitoring the epidemiology of Brucella strains at the national level is still lacking.MethodsA total of 600 Brucella isolates collected during 60 years (from 1953 to 2013) in China were genotyped by multiple locus variable-number tandem repeat analysis (MLVA) and the variation degree of MLVA11 loci was calculated by the Hunter Gaston Diversity Index (HGDI) values. The charts and map were processed by Excel 2013, and cluster analysis and epidemiological distribution was performed using BioNumerics (version 5.1).ResultsThe 600 representative Brucella isolates fell into 104 genotypes with 58 singleton genotypes by the MLVA11 assay, including B. melitensis biovars 2 and 3 (five main genotypes), B. abortus biovars 1 and 3 (two main genotypes), B. suis biovars 1 and 3 (three main genotypes), and B. canis (two main genotypes) respectively. While most B. suis biovar 1 and biovar 3 were respectively found in northern provinces and southern provinces, B. melitensis and B. abortus strains were dominant in China. Canine Brucellosis was only found in animals without any human cases reported. Eight Brucellosis epidemic peaks emerged during the 60 years between 1953 and 2013: 1955 – 1959, 1962 – 1969, 1971 – 1975, 1977 – 1983, 1985 – 1989, 1992 – 1997, 2000 – 2008 and 2010 – 2013 in China.ConclusionsBrucellosis has its unique molecular epidemiological patterns with specific spatial and temporal distribution according to MLVA.Trial registrationIDOP-D-16-00101.Electronic supplementary materialThe online version of this article (doi:10.1186/s40249-017-0296-0) contains supplementary material, which is available to authorized users.

Molecular epidemiological characterization ofBrucellaisolates from sheep and yaks in northwest China

“…The results also showed that B. melitensis was a predominant species in sheep and that most B. melitensis strains (71%) were subgrouped into the East Mediterranean group (genotype 42). These strains may be epidemiologically linked, some evidence of which was provided by the MLVA‐11 of these isolates in conjunction with 600 other strains from different regions in China (Tian et al., ).…”

“…Multilocus variable‐number tandem‐repeat analysis‐11 of 66 isolates found a novel genotype (genotype 369: 1‐5‐3‐13‐2‐2‐3‐2‐7‐41‐8), which emerged in panel 2B when the isolates were compared with other strains from different regions in China (Liu et al., ; Tian et al., ). The analysis indicated a dominant Brucella genotype that was relatively stable, but variations emerged in panel 2B within the bruce04, bruce16 and bruce30 loci.…”

“…Using the same software, clustering analysis was performed based on the categorical coefficient and unweighted pair group method using arithmetic averages (UPGMA) method. The resulting genotypes were compared using the web‐based Brucella 2016 MLVA database (http://mlva.u-psud.fr/) and published papers (Al Dahouk et al., ; Tian et al., ). All MLVA profiles have been submitted to the MLVA bank (http://microbesgenotyping.i2bc.paris-saclay.fr/).…”

“…All MLVA profiles have been submitted to the MLVA bank (http://microbesgenotyping.i2bc.paris-saclay.fr/). In addition, comparisons were made between isolates in this study and 600 strains from other Chinese provinces (Tian et al., ) to trace the evolutionary relationships of Brucella based on MLVA‐11. These strains were also utilized for a molecular epidemiological investigation of their transfer between livestock and humans.…”

“…These strains were also utilized for a molecular epidemiological investigation of their transfer between livestock and humans. Moreover, MLVA‐11 was used to determine the phylogeographic relationships among the 66 isolates (Liu et al., ; Tian et al., ).…”