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

Molecular epidemiological characteristics of osteoarthritis-associated Brucella melitensis in China: evidence from whole-genome sequencing-based analysis

BACKGROUND

Brucellosis, developing complications including arthritis, spondylitis, sacroiliitis, and osteomyelitis, is one of the most common zoonotic diseases in the current world which causes economic losses to the livestock industry and is a great public health concern. Brucella melitensis are the main pathogen of brucellosis epidemics in China, most of which are located in northern China. However, there is limited knowledge about the epidemiology of osteoarthritis-associated brucellosis. This study was aimed to reveal the prevalence of osteoarthritis-associated brucellosis in Inner Mongolia and also to investigate the molecular characteristics of B. melitensis isolates.

METHODS AND RESULTS

In 2018, the osteoarthritis symptoms of brucellosis in the Brucellosis department of a hospital in Inner Mongolia were investigated. Twenty osteoarthritis-associated B. melitensis strains, isolated from the inpatients in Inner Mongolia during 2013-2017, were subjected to whole genome sequencing. The multilocus sequence type (MLST) and core genome SNP (cgSNP) analysis were conducted to detect molecular epidemiological characteristics. The incidence of brucellosis osteoarthritis symptoms in males (85/120, 70.8%) was significantly higher than that in females (35/120, 29.2%), and the age of patients was concentrated between 41 and 60 years old. In silico analyses indicated ST8 was the prevalent sequence type and the transmission of osteoarthritis-associated B. melitensis among different geographical areas. All strains carry virulence genes, including cgs, lpsA, manCoAg, pgm, pmm, virB4, wbdA and wboA.

CONCLUSION

Our study showed the close epidemiologically connection of osteoarthritis-associated B. melitensis strains in northern China. And ST8 was the prevalent sequence type which need our attention.

Seroprevalence of Chlamydia abortus and Brucella spp. and risk factors for Chlamydia abortus in pigs from China

Chlamydiosis and brucellosis induced abortions have resulted in significant economic losses in the global livestock industry. Although there have been numerous reports on these two diseases in ruminants in China, limited information is available regarding the prevalence of Chlamydia abortus (C. abortus) and Brucella spp. infection in pigs. This study aimed to investigate the prevalence of C. abortus and Brucella spp. infections in pig serum using serology and to identify potential risk factors. In total, 2816 serum samples were collected from 12 provinces in China. The presence of C. abortus antibodies was determined using an enzyme-linked immunosorbent assay (ELISA), while the presence of Brucella spp. antibodies was examined using the Rose Bengal Plate Test (RBPT) and the Standard Agglutination Test (SAT). The seroprevalences of C. abortus and Brucella spp. were 8.38 % (236/2816) and 0.11 % (3/2816), respectively. Geographical location, season, and age were found to be risk factors associated with C. abortus infection in pig herds in China (p<0.01), and the seropositive rate for C. abortus in sow herds was strongly associated with the occurrence of abortion (p<0.01). Overall, in China, pigs exhibit a higher seroprevalence of C. abortus, whereas the prevalence of Brucella is limited. This study represents the first comprehensive survey of C. abortus and Brucella spp. in pig herds in China that established potential risk factors and provided data for the prevention and control of intraspecies and interspecies transmission of C. abortus to humans.

Molecular epidemiological characteristics of Brucella in Guizhou Province, China, from 2009 to 2021

Introduction

Brucellosis was made statutorily notifiable in 1955, in China, while in Guizhou Province, the pathogen of human brucellosis was isolated for the first time in 2011. However, currently, the brucellosis epidemic is becoming more and more severe in Guizhou Province. The type distribution and genetic characteristics of Brucella in Guizhou Province, as well as its evolutionary relationship with domestic and foreign strains, are still unclear.

Methods

MLST, MLVA, and rpoB typing techniques were used for the molecular epidemiological study of the 83 Brucella isolates in Guizhou province.

Results

Among the 83 Brucella strains, MLST identified three ST genotypes, of which ST39 is a newly reported type in China. MLVA-16 generated 49 genotypes, and MLVA-11 generated 5 known genotypes and 2 unreported genotypes. Six genotypes were identified by rpoB technology.

Discussion

MLVA has a high resolution, but differences at the Bruce 04 and 16 loci cannot exclude associations between epidemics, and combining MLST and rpoB typing methods for epidemiologic tracing can avoid erroneous judgments. Moreover, through the combined analysis of the three typing techniques, the possible origin of the new Brucella can be reasonably inferred, which is also conducive to promoting the subsequent research of the novel Brucella.

Vaccination with a Brucella ghost developed through a double inactivation strategy provides protection in Guinea pigs and cattle

Vaccination can prevent and control animal brucellosis. Currently, live attenuated vaccines are extensively used to prevent Brucella infection. However, traditional vaccines such as live attenuated vaccines are associated with biological safety risks for both humans and animals. The bacterial ghost (BG) is a new form of vaccine with great prospects. However, bacterial cells cannot be completely inactivated by biological lysis, conferring a safety risk associated with the vaccine. In this study, we developed a Brucella abortus A19 bacterial ghost (A19BG) through a double inactivation strategy with sequential biological lysis and hydrogen peroxide treatment. This strategy resulted in 100% inactivation of Brucella, such that viable bacterial cells were not detected even at an ultrahigh concentration of 10¹⁰ colony-forming units/mL. Furthermore, A19BG had a typical BG morphology and good genetic stability. Moreover, it did not induce adverse reactions in guinea pigs. The levels of antibodies, interferon-γ, interleukin-4, and CD4⁺ T cells in guinea pigs inoculated with the A19BG vaccine were similar to those inoculated with the existing A19 vaccine. Immunization with A19BG conferred a similar level of protection with that of A19 against Brucella melitensis M28 in both guinea pigs and cattle. In conclusion, the combination of biological lysis and H₂O₂-mediated inactivation is a safe and effective strategy that can serve as a reference for the preparation of BG vaccines.

Analysis of Clinical Manifestations of Acute and Chronic Brucellosis in Patients Admitted to a Public General Hospital in Northern China

Objective

To analyze the clinical features of patients with acute and chronic brucellosis in order to further improve the understanding of the disease.

Methods

The clinical data of 144 patients with brucellosis who were admitted to our hospital were selected for retrospective analysis and were divided into two groups: the acute phase group (n = 86) and the chronic phase group (n = 58), and the clinical characteristics of the acute and chronic phases of the disease were analyzed. The χ² test was used for countable data comparisons between the two groups.

Results

Brucella melitensis was found as the contact organism in 61 patients (70.93%) in the acute phase group and in 12 patients (20.69%) in the chronic phase group (p < 0.01). Brucella abortus was found as the contact organism in 14 patients (16.28%) in the acute phase group and in 38 patients (65.52%) in the chronic phase group (p < 0.01). The results showed that the respective prevalence of fever, excessive sweating, splenomegaly, and lymph node enlargement were higher in the acute phase group than in the chronic phase group (p < 0.01). The respective prevalence of testicular swelling and pain were higher in the acute phase group than in the chronic phase group (p < 0.05), while the prevalence of joint and muscle pain was higher in the chronic phase group than in the acute phase group (p < 0.01).

Conclusion

In Harbin, two types of clinical brucellosis, acute and chronic phase, infected sheep and cattle, respectively, are endemic at the same time, which complicates diagnosis. Besides, the clinical manifestations of brucellosis are complex and diverse, and they are often misdiagnosed and mistreated, leading to serious health injuries. Therefore, it is important to improve the understanding of disease characteristics in patients with acute and chronic brucellosis.

Evaluation and Differential Diagnosis of a Genetic Marked Brucella Vaccine A19ΔvirB12 for Cattle

Brucella abortus is an important zoonotic pathogen that causes severe economic loss to husbandry and poses a threat to human health. The B. abortus A19 live vaccine has been extensively used to prevent bovine brucellosis in China. However, it is difficult to distinguish the serological response induced by A19 from that induced by natural infection. In this study, a novel genetically marked vaccine, A19ΔvirB12, was generated and evaluated. The results indicated that A19ΔvirB12 was able to provide effective protection against B. abortus 2308 (S2308) challenge in mice. Furthermore, the safety and protective efficacy of A19ΔvirB12 have been confirmed in natural host cattle. Additionally, the VirB12 protein allowed for serological differentiation between the S2308 challenge/natural infection and A19ΔvirB12 vaccination. However, previous studies have found that the accuracy of the serological detection based on VirB12 needs to be improved. Therefore, we attempted to identify potential supplementary antigens with differential diagnostic functions by combining label-free quantitative proteomics and protein chip technology. Twenty-six proteins identified only in S2308 were screened; among them, five proteins were considered as potential supplementary antigens. Thus, the accuracy of the differential diagnosis between A19ΔvirB12 immunization and field infection may be improved through multi-antigen detection. In addition, we explored the possible attenuation factors of Brucella vaccine strain. Nine virulence factors were downregulated in A19ΔvirB12. The downregulation pathways of A19ΔvirB12 were significantly enriched in quorum sensing, ATP-binding cassette transporter, and metabolism. Several proteins related to cell division were significantly downregulated, while some proteins involved in transcription were upregulated in S2308. In conclusion, our results contribute to the control and eradication of brucellosis and provide insights into the mechanisms underlying the attenuation of A19ΔvirB12.

Global Comprehensive Literature Review and Meta-Analysis of Brucella spp. in Swine Based on Publications From 2000 to 2020

Background: Brucellosis, a zoonotic disease, infects various hosts, including swine and humans. It has reemerged in recent years as a public health concern, and current studies on brucellosis infection in swine have been conducted worldwide. However, no meta-analyses of global brucellosis infection in swine have been published. The aim of this study was to provide an overview of Brucella species (spp.) in swine worldwide and the factors associated with its persistence.

Results: We searched seven databases for published epidemiological studies on brucellosis in pigs, including the Chinese National Knowledge Infrastructure, Wanfang Data, SpringerLink, ScienceDirect, Web of Science, the VIP Chinese Journal Database and PubMed. We selected 119 articles published from January 1, 2000 to January 3, 2020 for inclusion in the meta-analysis and analyzed the data using a random-effects model. Funnel plots and Egger's test showed significant publication bias in the included studies. The results of the sensitivity analysis showed that our study was relatively stable and reliable. The prevalence of brucellosis in swine was 2.1% (95% CI: 1.6–2.6), of which the highest infection rate, which was found in Europe, was 17.4% (95% CI: 11.1–24.9). The prevalence in feral pigs (15.0%, 95% CI: 8.4–23.2) was higher than that in domestic pigs (1.1%, 95% CI 0.2–2.5). The prevalence in high-income countries (15.7%, 95% CI 8.0–25.3) was significantly higher than that in middle- (0.8%, 95% CI 0.5–1.1), and low-income countries (0.1%, 95% CI 0.0–0.2). The prevalence was highest in finishing pigs at 4.9% (95% CI 0.9–11.0), and lowest among suckling pigs at 0% (95% CI 0.0–0.5).

Conclusion: The Brucella prevalence in pig herds currently is distributed widely throughout the world. In some countries, swine brucellosis may be a neglected zoonotic disease. We recommend long-term monitoring of the prevalence of brucellosis in domestic and wild pig herds. Attention should also be paid to animal welfare on intensive pig farms; controlling the breeding density may play an important role in reducing the spread of brucellosis among pigs.

Emerging diversity and ongoing expansion of the genus Brucella

Remarkable genetic diversity and breadth of host species has been uncovered in the Brucella genus over the past decade, fundamentally changing our concept of what it means to be a Brucella. From ocean fishes and marine mammals, to pond dwelling amphibians, forest foxes, desert rodents, and cave-dwelling bats, Brucella have revealed a variety of previously unknown niches. Classical microbiological techniques have been able to help us classify many of these new strains but at times have limited our ability to see the true relationships among or within species. The closest relatives of Brucella are soil bacteria and the adaptations of Brucella spp. to live intracellularly suggest that the genus has evolved to live in vertebrate hosts. Several recently discovered species appear to have phenotypes that are intermediate between soil bacteria and core Brucella, suggesting that they may represent ancestral traits that were subsequently lost in the traditional species. Remarkably, the broad relationships among Brucella species using a variety of sequence and fragment-based approaches have been upheld when using comparative genomics with whole genomes. Nonetheless, genomes are required for fine-scale resolution of many of the relationships and for understanding the evolutionary history of the genus. We expect that the coming decades will reveal many more hosts and previously unknown diversity in a wide range of environments.

Molecular characteristics of Brucella melitensis isolates from humans in Qinghai Province, China

BACKGROUND

The prevalence of human brucellosis in Qinghai Province of China has been increasing rapidly, with confirmed cases distributed across 31 counties. However, the epidemiology of brucellosis transmission has not been fully elucidated. To characterize the infecting strains isolated from humans, multiple-locus variable-number tandem repeats analysis (MLVA) and whole-genome single-nucleotide polymorphism (SNP)-based approaches were employed.

METHODS

Strains were isolated from two males blood cultures that were confirmed Brucella melitensis positive following biotyping and MLVA. Genomic DNA was extracted from these two strains, and whole-genome sequencing was performed. Next, SNP-based phylogenetic analysis was performed to compare the two strains to 94 B. melitensis strains (complete genome and draft genome) retrieved from online databases.

RESULTS

The two Brucella isolates were identified as B. melitensis biovar 3 (QH2019001 and QH2019005) following conventional biotyping and were found to have differences in their variable number tandem repeats (VNTRs) using MLVA-16. Phylogenetic examination assigned the 96 strains to five genotype groups, with QH2019001 and QH2019005 assigned to the same group, but different subgroups. Moreover, the QH2019005 strain was assigned to a new subgenotype, IIj, within genotype II. These findings were then combined to determine the geographic origin of the two Brucella strains.

CONCLUSIONS

Utilizing a whole-genome SNP-based approach enabled differences between the two B. melitensis strains to be more clearly resolved, and facilitated the elucidation of their different evolutionary histories. This approach also revealed that QH2019005 is a member of a new subgenotype (IIj) with an ancient origin in the eastern Mediterranean Sea.

Cell membrane components of Brucella melitensis play important roles in the resistance of low-level rifampicin

Brucella spp. are facultative intracellular pathogens that can persistently colonize host cells and cause the zoonosis- brucellosis. The WHO recommended a treatment for brucellosis that involves a combination of doxycycline, rifampicin, or streptomycin. The aim of this study was to screen rifampicin-resistance related genes by transcriptomic analysis and gene recombination method at low rifampicin concentrations and to predict the major rifampicin- resistance pathways in Brucella spp. The results showed that the MIC value of rifampicin for B. melitensis bv.3 Ether was 0.5 μg / mL. Meanwhile, B. melitensis had an adaptive response to the resistance of low rifampicin in the early stages of growth, while the SNPs changed in the rpoB gene in the late stages of growth when incubated at 37°C with shaking. The transcriptome results of rifampicin induction showed that the functions of significant differentially expressed genes were focused on metabolic process, catalytic activity and membrane and membrane part. The VirB operon, β-resistance genes, ABC transporters, quorum-sensing genes, DNA repair- and replication -related genes were associated with rifampicin resistance when no variations of the in rpoB were detected. Among the VirB operons, VirB7-11 may play a central role in rifampicin resistance. This study provided new insights for screening rifampicin resistance-related genes and also provided basic data for the prevention and control of rifampicin-resistant Brucella isolates.

Brucella spp. are facultative intracellular pathogens that can persistently colonize host cells and cause the zoonosis- brucellosis. The WHO recommended a treatment for brucellosis that involves a combination of doxycycline, rifampicin, or streptomycin. Rifampicin-resistance related genes were screened by transcriptomic analysis and gene recombination method at low rifampicin concentrations and the major rifampicin- resistance pathways in Brucella spp were predicted. The results showed that the VirB operon, β-resistance genes, ABC transporters, quorum-sensing genes, DNA repair- and replication -related genes were associated with rifampicin resistance when no variations of the in rpoB were detected. Among the VirB operons, VirB7-11 may play a central role in rifampicin resistance.

Abortion and various associated risk factors in dairy cow and sheep in Ili, China

We studied livestock abortion and various associated risk factors in the Ili region of northwest China. Livestock abortion prevalence was estimated and correlated with infections (Brucellosis, Salmonellosis, Mycoplasma and Chlamydia seropositivity) and management (farming type and contact with other herds/flocks) risk factors. A total of 2996 serum samples (1406 cow, 1590 sheep) were identified by RBPT (Rose Bengal Plate Test) and c-ELISA (competitive-enzyme linked immunosorbent assay), and they showed the overall seroprevalence of brucellosis in the study area was cow 6.76%, sheep 9.50%. The seroprevalence of brucellosis in X county was cow 7.06%, sheep 9.12%; in H county was cow 11.70%, sheep 10.80%; and in Q county was cow 4.22%, sheep 9.11%. The overall seroprevalence of Mycoplasma in the study area was cow 3.20%, sheep 6.42%. The seroprevalence of Mycoplasma in X county was cow 3.39%, sheep 7.98%; in H county was cow 5.26%, sheep 9.97%; and in Q county was cow 2.11%, sheep 4.33%. The Odds ratio of brucellosis for cow and sheep, respectively, were 45.909 [95% CI 26.912-78.317, P<0.001] and 70.507 [95% CI 43.783-113.544, P<0.001] times higher than other abortion-related factors including mixed farming, contact with other flocks and Mycoplasma infection. A total of 54 samples, including aborted cow (22), sheep (30) fetuses and milk samples (2), were identified as Brucella melitensis (B. melitensis) positive. A total of 38 Brucella were isolated from 16 aborted cow, 20 sheep fetuses and 2 milk samples. All of these isolates were identified, and confirmed, as B. melitensis. A phylogenetic tree showed that the Brucella isolates closely matched the B. melitensis biovar 3 isolated in Inner Mongolia, China, and B. melitensis isolated from Norway and India. These results suggest that B. melitensis biovar 3 is the main pathogen responsible for cow and sheep abortion and also pose a human health risk. Additionally, livestock reproduction can also be influenced by Mycoplasma infection and managerial factors (farming type and contact with other herds/flocks), especially in remote areas.

Multiple locus variable number tandem repeat analysis for the characterization of wild feline Bartonella species and subspecies

Bartonella genus includes an increasing number of species and subspecies, especially among wild felids, the positioning of which, with regards to the zoonotic species Bartonella henselae, is important to determine. The aim of this study was to test the ability of a molecular typing technique to distinguish between various Bartonella isolates obtained from four different species of free-ranging and captive wild felids and to identify key profiles or markers allowing differentiating them from each other and/or from B. henselae or B. koehlerae. A molecular typing technique for B. henselae based on the polymorphism of variable number tandem repeat units (VNTR) called MLVA (Multiple Locus VNTR Analysis) was applied to 24 Bartonella isolates from free-ranging or captive wild felids, 19 of which were obtained from California and five from three countries in Southern Africa, and compared with 49 B. henselae isolates from cats, dog or humans from the United States including the human ATCC (American Type Culture Collection) reference strain, B. henselae Houston 1. MLVA allowed distinguishing Bartonella isolates from wild felids from either B. henselae or B. koehlerae. We confirmed infection of semi-captive cheetahs with an isolate similar to a Californian bobcat isolate. MLVA also confirmed the unique profile of a free-ranging cheetah isolate from Namibia. Specific profiles were observed making MVLA a useful identification/classification tool of these wild felid isolates and suggesting that they are highly adapted to a specific feline reservoir. Finally, circulation of B. henselae isolates between domestic cats, wild felids and humans is likely occurring, based on the close allelic profiles of some isolates.

Molecular epidemiology of Brucella abortus strains from cattle in Inner Mongolia, China

Although the prevalence of brucellosis in Inner Mongolia Autonomous Region currently remains high, data available on the epidemiological of circulating Brucella abortus strains were limited. A total of 75 isolates obtained from cattle, sheep, and humans were analysed using both the classical method and multiple locus variable-number tandem repeat analysis (MLVA). There are at least three B. abortus biovars (1, 3 and 6) in this region, and B. abortus biovar 3 is the predominant one. Ten known MLVA-11 genotypes were identified, of which five genotypes (72, 75, 78, 82 and 210) were shared among strains from this study and others previously collected in two to seven different nations, suggesting that this population has multiple geographic origins. An MLVA-16 assay sorted the 75 B. abortus strains into two groups (I and II), 5 clusters (A-E) and 44 genotypes (GT1-44), with 26 unique genotypes represented by single isolates, indicating that these B. abortus brucellosis cases were not directly epidemiologically related. The remaining 18 shared genotypes (among a total of 47 isolates) were represented by two to eight isolates, suggesting that there were epidemiologically related pathogens from each shared genotype among the cases. Importantly, the cluster B1 branch including 22 cluster isolates with identical or similar genotypes confirmed the occurrence of a concentrated outbreak epidemic in the eastern region during 1988-1995. This work will contribute to better understanding of B. abortus brucellosis epidemiology in Inner Mongolia.

First isolation and characterization of Brucella suis from yak

Brucella spp., facultative intracellular pathogens that can persistently colonize animal host cells and cause zoonosis, affect public health and safety. A Brucella strain was isolated from yak in Qinghai Province. To detect whether this isolate could cause an outbreak of brucellosis and to reveal its genetic characteristics, several typing and whole-genome sequencing methods were applied to identify its species and genetic characteristics. Phylogenetic analysis based on MLVA and whole-genome sequencing revealed the genetic characteristics of the isolated strain. The results showed that the isolated strain is a B. suis biovar 1 smooth strain, and this isolate was named B. suis QH05. The results of comparative genomics and MLVA showed that B. suis QH05 is not a vaccine strain. Comparison with other B. suis strains isolated from humans and animals indicated that B. suis QH05 may be linked to specific animal and human sources. In conclusion, B. suis QH05 does not belong to the Brucella epidemic species in China, and as the first isolation of B. suis from yak, this strain expands the host range of B. suis.

Molecular Characteristics of Brucella Isolates Collected From Humans in Hainan Province, China

Brucellosis has been reported in several regions of Hainan Province, but the extent of the disease has not been fully elucidated. Conventional biotyping methods, multiple locus variable number tandem repeats analysis (MLVA), and single-nucleotide polymorphisms (SNPs) from draft genome sequencing were employed to characterize the strains. There were four biovars (Brucella melitensis bv. 1, 2, and 3 and Brucella suis bv. 3) detected, which showed that the biovar diversity of Brucella in Hainan is higher than in other areas of China. Both B. melitensis bv. 3 and B. suis bv. 3 were dominant species and showed epidemiology patterns that were compatible with both southern and northern China. Eight of MLVA-11 genotypes were known (31, 111, 116, 120, 136, 291, 297, and 345), and the remaining seven were novel (HN11-1 to HN11-7); these data showed that Brucella strains in this study had multiple geographic origins and exhibited characteristics of origin and evolution of co-existing imported and Hainan specific lineage. A total of 41 strains were found, belonging to 37 unique genotypes that each represented a single strain, which suggests that these strains were not directly related epidemiologically and indicates that the epidemic characteristics of human brucellosis in Hainan was dominated by sporadic strains. The high HGDI values were observed in MLVA-8, MLVA-11, and MLVA-16 among two species, suggesting considerable genetic diversity among these species. MST is characterized based on MLVA-16 that was found both throughout China and on a global level and showed that strains of this study had significant genetic differences with strains from many parts of the globe and seemingly represent a unique genetic lineage. Whole-genome SNP analysis showed that four B. melitensis were closely related to strains from China's northern provinces, and the source of infection was partly of human brucellosis in this province that may have been from these regions. The B. suis were closely related to strains from the United States, and further investigation of the transportation of animals, such as pigs, is needed to elucidate the origins of these strains.

Whole-genome sequencing of rough Brucella melitensis in China provides insights into its genetic features

Brucella spp. can cause the zoonosis brucellosis, which affects public health and safety and even economic development. B. melitensis has a smooth phenotype, while 28 B. melitensis isolates had a rough phenotype in 2018. In this study, rough phenotype detection and whole genome sequencing methods were used to analyze the genetic features of rough B. melitensis. A drug susceptibility test was also performed. The results showed that the rough B. melitensis strains originated from strains isolated in China rather than from foreign strains. Furthermore, an MS tree showed that 9 complexes to be epidemic in China. For the rough B. melitensis strains, expression of the metabolic function genes varied in the earlier stages of evolution compared to the cellular process and signalling function genes. Expression of some transcriptional regulatory factors also varied in the later stages of evolution, and compared to MFS transporter genes, ABC transporter genes varied in the earlier stages. Moreover, as there was no significant difference in rifampicin, doxycycline and streptomycin susceptibility between the smooth and rough B. melitensis strains, treatment of brucellosis was not affected by strain type. This study provided important information for understanding the genetics and evolution of rough B. melitensis in China.

Investigation of the molecular characteristics of Brucella isolates from Guangxi Province, China

Background

Human brucellosis has become a severe public health problem in China’s Guangxi Province, and there has been higher prevalence of brucellosis in this region after 2010. Both multiple locus variable-number tandem repeat analysis (MLVA) and multilocus sequence typing (MLST) assay schedules were used to genotype isolates and determine relationships among isolates.

Results

A total of 40 isolates of Brucella were obtained from humans, pigs, and dogs from 1961 to 2016. There were at least three species of Brucella detected in Guangxi Province, Brucella melitensis, Brucella suis, and Brucella canis, with 16, 17, and 7 isolates, respectively. Of which B. suis biovar 3 was the predominant species resulting in pig brucellosis in the area examined before 2000s. Moreover, B. melitensis biovar 3 was found to be mainly responsible for human brucellosis during 2012–2016. All B. melitensis isolates in this study belonged to East Mediterranean lineage. MLVA-11 genotype 116 was the dominant genotype and represented 81.2% of the isolates. MLVA cluster analysis showed there to be 44% (7/16) brucellosis cases caused by B. melitensis with a profile of outbreak epidemic from 2012 to 2016. However, nearly 83.3% (20/24) of brucellosis cases resulting from both B. suis and B. canis showed no epidemiological links or sporadic characteristics. MLVA-16 analysis confirmed extensive genotype-sharing events between B. melitensis isolates from Guangxi and other northern provinces within China. These data revealed that there are potential epidemiology links among these strains. B. suis strains of this study showed a unique genetic lineage at the global level and may have existed historically in this area. However, present B. canis isolates were closely related to previously reported isolates in Korea, where they may have originated. MLST typing showed that the population structure of Brucella strains had changed considerably in this province; ST17 and ST21, two previously predominant populations appeared to have been replaced by recently emerging ST8 group.

Conclusions

Our investigation data have inspired the hypothesis that Guangxi Province had been subject to an imported human brucellosis epidemic. Our data suggest that strains found in Northern regions of China are the principal source of infections in recent cases of human brucellosis in Guangxi Province. Comparative genomic analysis from more strains is necessary to confirm this hypothesis. This work will facilitate better understanding of the epidemiology and improve the effectiveness of control and prevention of brucellosis in this region.

Investigation of the molecular epizootiological characteristics and tracking of the geographical origins of Brucella canis strains in China

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.

A case report on mother-to-child transmission of Brucella in human, China

Background

Human brucellosis is endemic in China and commonly occurs through contact with infected animals from working with livestock or consumption of unpasteurized dairy products. Although rare, human-to-human, and possible sexual transmission, of Brucella has been reported. In this report, we describe a case of likely mother-to-child transmission of Brucella in Hunan Province, China.

Case presentation

Between June and October 2016, a 28-year old man sought care for testicular swelling and pain at several health facilities. His 26-year old wife developed intermittent fever along with right thigh and hip pain between November 2016 and February 2017 respectively. On April 5, 2017, the female patient delivered a male neonate at 34 weeks of gestation through natural labor. The child’s venal blood sample was cultured on April 5, 2017. Brucella was isolated and identified on April 12, 2017. On the same date, serum antibodies of the father and mother were above 1:100 (based on the serum agglutination test [SAT]). The strains isolated from the mother and neonate were identified as Brucella melitensis biotype 1.

Conclusions

This report highlights a family cluster of brucellosis. Culture results strongly support mother-to-child transmission, and a high probability of sexual transmission from husband to wife.

Genetic Characterization of Animal Brucella Isolates from Northwest Region in China

Animal brucellosis is a reemerging disease in China, particular in northwest China. The Brucella species (even genus) are highly conserved; therefore the use of Multilocus sequencing typing (MLST: based on conserved housekeeping loci) is more suitable for discrimination at species or biovar level on Brucella. In this study, MLST was used to analyze the characterization of Brucella from sheep and yaks during 2015 and 2016. All 66 isolates were collected from northwest China, including Inner Mongolia, Xinjiang, Qinghai, and Gansu provinces. Isolates were cultured on Brucella agar medium and identified by MLST. MLST identified five ST types: ST8 (n = 55), ST7 (n = 2), ST3 (n = 5), ST1 (n = 2), and ST14 (n = 2). This analysis revealed that B. melitensis isolates exhibited high single genotypes (ST8) in the most northwest China. MLST of isolates provides helpful information on understanding genetic characterization of Brucella in northwest China.

Enzootic situation and molecular epidemiology of Brucella in livestock from 2011 to 2015 in Qingyang, China

A large-scale survey was conducted in domestic animal populations from 2011 to 2015 in Qingyang, China. A total of 448,398 animals from different districts of Qingyang were tested for the presence of Brucella-specific antibodies using the Rose Bengal Plate Test (RBPT) and the Standard Agglutination Test (SAT). From 2011 to 2015, the yearly average positive rates were between 0.04 and 4.75% in the eight counties tested. In addition, the prevalence rates were between 0 and 9.96% in these eight counties. Sheep was the dominant host of Brucella in Qingyang, and the prevalence rate in sheep (2.74%) was higher than those in the other animals tested. Identification of 10 Brucella isolates from sheep confirmed that the epidemic strains were B. melitensis biovar 3 (n = 9) and B. melitensis biovar 1 (n = 1). MLVA-11 (multiple-locus variable-number tandem repeat analysis) analysis of the 10 isolates showed three genotypes: genotype 116 (n = 8), genotype 115 (n = 1) and genotype 136 (n = 1). Furthermore, analysis of the whole-genome sequences of the representative B. melitensis strain QY1 indicated that this isolate was closely related to isolates from China and India. The results of serum epidemiology confirmed that the region of northern Qingyang was a critical Brucella epidemic area and that the disease showed a rising trend, especially from 2013 to 2015. An analysis of the isolate genotypes suggested that sheep brucellosis mainly resulted from conventional B. melitensis (East Mediterranean group), although the external strain (American group) also occurred in Qingyang.

Multiple Locus Variable-Number Tandem-Repeat and Single-Nucleotide Polymorphism-Based Brucella Typing Reveals Multiple Lineages in Brucella melitensis Currently Endemic in China

Brucellosis is a worldwide zoonotic disease caused by Brucella spp. In China, brucellosis is recognized as a reemerging disease mainly caused by Brucella melitensis specie. To better understand the currently endemic B. melitensis strains in China, three Brucella genotyping methods were applied to 110 B. melitensis strains obtained in past several years. By MLVA genotyping, five MLVA-8 genotypes were identified, among which genotypes 42 (1-5-3-13-2-2-3-2) was recognized as the predominant genotype, while genotype 63 (1-5-3-13-2-3-3-2) and a novel genotype of 1-5-3-13-2-4-3-2 were second frequently observed. MLVA-16 discerned a total of 57 MLVA-16 genotypes among these Brucella strains, with 41 genotypes being firstly detected and the other 16 genotypes being previously reported. By BruMLSA21 typing, six sequence types (STs) were identified, among them ST8 is the most frequently seen in China while the other five STs were firstly detected and designated as ST137, ST138, ST139, ST140, and ST141 by international multilocus sequence typing database. Whole-genome sequence (WGS)-single-nucleotide polymorphism (SNP)-based typing and phylogenetic analysis resolved Chinese B. melitensis strains into five clusters, reflecting the existence of multiple lineages among these Chinese B. melitensis strains. In phylogeny, Chinese lineages are more closely related to strains collected from East Mediterranean and Middle East countries, such as Turkey, Kuwait, and Iraq. In the next few years, MLVA typing will certainly remain an important epidemiological tool for Brucella infection analysis, as it displays a high discriminatory ability and achieves result largely in agreement with WGS-SNP-based typing. However, WGS-SNP-based typing is found to be the most powerful and reliable method in discerning Brucella strains and will be popular used in the future.

Molecular epidemiological characterization of Brucella isolates from sheep and yaks in northwest China

Animal brucellosis is a re-emerging disease in China with high prevalence in the northwest region. A total of 66 isolates of Brucella were recovered from sheep and yaks in the Inner Mongolia, Xinjiang, Qinghai and Gansu provinces of northwest China in 2015 and 2016. Using classical biotyping and the Brucella AMOS PCR assay, all isolates were identified as Brucella melitensis biovar 3 (n = 58), B. melitensis biovar 1 (n = 1), Brucella abortus (n = 5), or Brucella suis biovar 3 (n = 2), and B. melitensis biovar 3 was found to be mainly responsible for sheep brucellosis in northwest China. Multilocus variable-number tandem-repeat analysis (MLVA) was used to identify the epidemiological relationships among the isolates and to assess their genetic diversity. Multilocus variable-number tandem-repeat analysis-16 identified 46 genotypes in these populations, including 37 unique and nine shared genotypes. Multilocus variable-number tandem-repeat analysis-11 showed that 71% of the isolates (47 of 66) were genotype 116 (1-5-3-13-2-2-3-2-4-41-8), a characteristic subgroup of the East Mediterranean group, showing that isolates from different geographical areas exhibit similar epidemiological characteristics in different regions and may be epidemiologically linked. Multilocus variable-number tandem-repeat analysis-11 also revealed that an isolate from Inner Mongolia had a novel genotype, 369 (1-5-3-13-2-2-3-2-7-41-8). Multilocus variable-number tandem-repeat analysis-16 genotyping of northwest China Brucella isolates allows a better understanding of the epidemiology of animal brucellosis in this region. This study is the first analysis of B. melitensis in Gansu province, and the results confirmed that in this province, isolates of this species are disorderly and unsystematic.