Investigation of the molecular epizootiological characteristics and tracking of the geographical origins ofBrucella canisstrains in China

Abstract

Brucellosis is a global pandemic infectious zoonosis. Brucella canis is a rare source of human brucellosis in China, and its public health significance remains under debate. Moreover, data pertaining to the epizootiological characteristics and geographical origin of B. canis on a nationwide scale are limited, and the risk to public safety posed by B. canis infections is unknown. The MLVA (multilocus variable‐number tandem repeat analysis) assay can be helpful to analyse epidemiological correlations among Brucella isolates and to track their geographic origins. To accomplish this task, MLVA‐16 was used to analyse the epidemiological links of 63 isolates obtained from dogs and humans. Sixty‐three B. canis strains were sorted into three large clusters (A, B and C) and 50 different genotypes (GT1–50), and 43 unique genotypes were represented by single isolates, suggesting that these strains had no obvious epidemiological links and that canine brucellosis is predominantly sporadic in China. The other seven shared genotypes (among a total of 20 isolates) were each represented by two to eight isolates, indicating that strains from each shared genotype were epidemiologically correlated. Five of the shared genotypes were from 16 strains obtained from Beijing, indicating that canine brucellosis in Beijing originates from multipoint outbreaks with multiple sources of infection. Based on comprehensive case analysis of clinical B. canis infection, we preliminarily suggest that human B. canis infections are associated with Mycoplasma pneumoniae infection that results in decreased patient immunity. B. canis may have limited epidemiological significance for the healthy population, but it remains a significant threat to the canine breeding industry and to humans who come into close contact with dogs. Based on MLVA‐11 data, B. canis strains were clustered into 16 genotypes and divided into five evolutionary branches; these data confirm that this population covers an extensive geographic area and exhibits characteristics of the origin and evolution of co‐existing introduced and locally native lineages. We believe this study will contribute to strengthening efforts to prevent and control canine brucellosis and to improve public understanding of the health risks posed by B. canis.

Molecular Epidemiology Characteristics of Brucella abortus Strains in China and Their Relationships with World Lineages

“…Notably, five panel 2B markers had a high Hunter-Gaston index, and bruce07 is the most helpful locus for genotyping B. abortus in China. This result was consistent with B. canis data in China; there were at least two alleles for each of the 16 loci investigated by the MIVA approach [12]. However, this feature is different from the results of studies of B. melitensis diversity in China.…”

“…Both the categorical coefficient and unweighted pair group methods were applied to the clustering analysis. MLVA-11 was used to investigate the geographical origins between our isolates [25,26] and 1,482 isolates from the MLVA bank (http://microbesgenotyping.i2bc.paris-saclay.fr/databases) (Table S2), and minimum-spanning trees were constructed using the goeBURST algorithm with PHYOVIZ 2.0 [27]. The MLVA-16 approach was applied to the genetically related investigation between strains from those reported in China (n = 100) (Table S1) and at the global level (n = 1525) (Table S3).…”

“…A bio-typing assay is time consuming and difficult to interpret due to limited standardization of the typing reagents, but it was useful for Brucella strain identification and species differentiation [11]. Moreover, multi-locus variable-number tandem repeat assays (MLVA) are a genetic approach with high discriminatory power in the Brucella genus, providing a fine-scale resolution among isolates and allowing the determination of the source of infection, geographical origin, and spread pattern of disease [12,13]. The whole-genome sequencing-single-nucleotide polymorphism (WGS-SNP) approach is used to establish phylogenetic relationships of Brucella isolates [14,15].…”

Molecular Epidemiology Characteristics of Brucella Abortus Strains in China and Their Relationships With World Lineages

“…Notably, ve panel 2B markers had a high Hunter-Gaston index, and bruce07 is the most helpful locus for genotyping B. abortus in China. This result was consistent with B. canis data in China; there were at least two alleles for each of the 16 loci investigated by the MIVA approach [20]. However, this feature is different from the results of studies of B. melitensis diversity in China.…”

Seroprevalence of human brucellosis and molecular characteristics of Brucella strains in Inner Mongolia Autonomous region of China, from 2012 to 2016

“…The genus is represented by 12 known species [3]; among these, Brucella melitensis, Brucella abortus, and Brucella suis have a particularly critical and extensive impact on human health and the development of animal husbandry [4,5]. Brucellosis is a common zoonosis in northern China [6], However, the Inner Mongolia Autonomous Region is an area in China of known endemicity, with the highest incidence rate, accounting for approximately 40% of reported cases in the country during 2011-2016 [7,8]. The incidence and epidemiology of brucellosis in this region represent the characteristics of this disease in China.…”