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Veterinary Pathology Nov 2014Fifty years ago, bacteria in the genus Brucella were known to cause infertility and reproductive losses. At that time, the genus was considered to contain only 3... (Review)
Review
Fifty years ago, bacteria in the genus Brucella were known to cause infertility and reproductive losses. At that time, the genus was considered to contain only 3 species: Brucella abortus, Brucella melitensis, and Brucella suis. Since the early 1960s, at least 7 new species have been identified as belonging to the Brucella genus (Brucella canis, Brucella ceti, Brucella inopinata, Brucella microti, Brucella neotomae, Brucella ovis, and Brucella pinnipedialis) with several additional new species under consideration for inclusion. Although molecular studies have found such high homology that some authors have proposed that all Brucella are actually 1 species, the epidemiologic and diagnostic benefits for separating the genus based on phenotypic characteristics are more compelling. Although pathogenic Brucella spp have preferred reservoir hosts, their ability to infect numerous mammalian hosts has been increasingly documented. The maintenance of infection in new reservoir hosts, such as wildlife, has become an issue for both public health and animal health regulatory personnel. Since the 1960s, new information on how Brucella enters host cells and modifies their intracellular environment has been gained. Although the pathogenesis and histologic lesions of B. abortus, B. melitensis, and B. suis in their preferred hosts have not changed, additional knowledge on the pathology of these brucellae in new hosts, or of new species of Brucella in their preferred hosts, has been obtained. To this day, brucellosis remains a significant human zoonosis that is emerging or reemerging in many parts of the world.
Topics: Animals; Animals, Wild; Brucella; Brucella Vaccine; Brucellosis; Communicable Diseases, Emerging; Disease Models, Animal; Disease Reservoirs; Humans; Zoonoses
PubMed: 24981716
DOI: 10.1177/0300985814540545 -
PloS One 2014In China, brucellosis is an endemic disease typically caused by Brucella melitensis infection (biovars 1 and 3). Brucella canis infection in dogs has not traditionally...
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.
Topics: Animals; Brucella canis; Brucellosis; China; Disease Outbreaks; Dog Diseases; Dogs; Gene Amplification; Genes, Bacterial; Genetic Markers; Genotype; Minisatellite Repeats; Molecular Sequence Data; Multilocus Sequence Typing; Phylogeny; Polymorphism, Single Nucleotide
PubMed: 24465442
DOI: 10.1371/journal.pone.0084862 -
MSphere May 2020is a Gram-negative, facultative intracellular bacterium and the causative agent of canine brucellosis, a highly contagious disease of dogs that can be transmitted to...
is a Gram-negative, facultative intracellular bacterium and the causative agent of canine brucellosis, a highly contagious disease of dogs that can be transmitted to humans. Unfortunately, no vaccine is available to prevent infection. We recently characterized the kinetics of infection in the mouse model, establishing the required dose necessary to achieve systemic infection. The objective of this study was to investigate the utility of the mouse model in assessing canine brucellosis vaccine candidates and to subsequently investigate the safety and efficacy of a live attenuated vaccine, the RM6/66 Δ strain. Mice vaccinated with a dose of 10 CFU of the vaccine strain by both intraperitoneal and subcutaneous routes were afforded significant protection against organ colonization and development of histopathologic lesions following intraperitoneal challenge. Addition of an adjuvant or a booster dose 2 weeks following initial vaccination did not alter protection levels. Vaccination also resulted in a robust humoral immune response in mice, and RM6/66 Δ was capable of activating canine dendritic cells These data demonstrate that the RM6/66 Δ strain shows promise as a vaccine for canine brucellosis and validates the mouse model for future vaccine efficacy studies. Canine brucellosis, caused by , is the primary cause of reproductive failure in dogs and represents a public health concern due to its zoonotic nature. Cases in dogs in the United States have been increasing due to the persistent nature of the bacterium, deficiencies in current diagnostic testing, and, most importantly, the lack of a protective vaccine. Current estimates place the seroprevalence of in the southern United States at 7% to 8%, but with the unprecedented rates of animals moving across state and international borders and the lack of federal regulations in regard to testing, the true seroprevalence of in the United States may very well be higher. Vaccination represents the most effective method of brucellosis control and, in response to the demand for a vaccine against , we have developed the live attenuated RM6/66 Δ vaccine strain capable of protecting mice against challenge.
Topics: Adjuvants, Immunologic; Animals; Antibodies, Bacterial; Brucella Vaccine; Brucella canis; Brucellosis; Disease Models, Animal; Female; Immunity, Humoral; Injections, Intraperitoneal; Injections, Subcutaneous; Mice; Mice, Inbred C57BL; Seroepidemiologic Studies; Spleen; Vaccines, Attenuated
PubMed: 32434839
DOI: 10.1128/mSphere.00172-20 -
Veterinary Microbiology Dec 2002The genus Brucella contains alpha-Proteobacteria adapted to intracellular life within cells of a variety of mammals. Controversy has arisen concerning Brucella internal... (Review)
Review
The genus Brucella contains alpha-Proteobacteria adapted to intracellular life within cells of a variety of mammals. Controversy has arisen concerning Brucella internal taxonomy, and it has been proposed that the DNA-DNA hybridization-based genomospecies concept be applied to the genus. According to this view, only one species, Brucella melitensis, should be recognized, and the classical species should be considered as biovars (B. melitensis biovar melitensis; B. melitensis biovar abortus; etc.). However, a critical reappraisal of the species concept, a review of the population structure of bacteria and the analysis of Brucella genetic diversity by methods other than DNA-DNA hybridization show that there are no scientific grounds to apply the genomospecies concept to this genus. On the other hand, an enlarged biological species concept allows the definition of Brucella species that are consistent with molecular analyses and support the taxonomical standing of most classical species. Both the host range as a long-recognized biological criterion and the presence of species-specific markers in outer membrane protein genes and in other genes show that B. melitensis, B. abortus, B. ovis, B. canis and B. neotomae are not mere pathovars (or nomenspecies) but biologically meaningful species. The status of B. suis is, however, less clear. These approaches should be useful to define species for the marine mammal Brucella isolates, as illustrated by the grouping of the isolates from pinnipeds or from cetaceans by omp2 gene analysis. It is shown that a correct Brucella species definition is important to understand the evolution of the genus.
Topics: Biological Evolution; Brucella; Brucella melitensis; Classification; DNA, Bacterial; Phylogeny; Species Specificity
PubMed: 12414145
DOI: 10.1016/s0378-1135(02)00210-9 -
The Veterinary Clinics of North... Jan 2018Discospondylitis can affect dogs of any age and breed and may be seen in cats. Although radiography remains the gold standard, advanced imaging, such as CT and MRI, has... (Review)
Review
Discospondylitis can affect dogs of any age and breed and may be seen in cats. Although radiography remains the gold standard, advanced imaging, such as CT and MRI, has benefits and likely allows earlier diagnosis and identification of concurrent disease. Because discospondylitis may affect multiple disk spaces, imaging of the entire spine should be considered. There is a lengthening list of causative etiologic agents, and successful treatment hinges on correct identification. Image-guided biopsy should be considered in addition to blood and urine cultures and Brucella canis screening and as an alternative to surgical biopsy in some cases.
Topics: Animals; Anti-Infective Agents; Cat Diseases; Cats; Diagnosis, Differential; Dog Diseases; Dogs; Lumbosacral Region; Osteomyelitis; Risk Factors; Spondylitis; Thoracic Vertebrae
PubMed: 28964545
DOI: 10.1016/j.cvsm.2017.08.007 -
PloS One 2017Brucella canis infection is an important cause of late-term abortion in pregnant bitches. The pathophysiological mechanisms leading to B. canis-induced abortion are...
Brucella canis infection is an important cause of late-term abortion in pregnant bitches. The pathophysiological mechanisms leading to B. canis-induced abortion are unknown, but heavily infected trophoblasts are consistently observed. As trophoblasts responses to other pathogens contribute to placental inflammation leading to abortion, the aim of the present study was to characterize the cytokine response of canine trophoblasts to B. canis infection. To achieve this, trophoblasts isolated from term placenta of healthy female dogs were infected with B. canis, culture supernatants were harvested for cytokine determinations, and the load of intracellular viable B. canis was determined at different times post-infection. Additionally, cytokine responses were assessed in non-infected trophoblasts stimulated with conditioned media (CM) from B. canis-infected canine monocytes and neutrophils. Finally, cytokine response and bacteria replication were assessed in canine placental explants infected ex vivo. B. canis successfully infected and replicated in primary canine trophoblasts, eliciting an increase in IL-8 and RANTES (CCL5) secretion. Moreover, the stimulation of trophoblasts with CM from B. canis-infected monocytes and neutrophils induced a significant increase in IL-8, IL-6 and RANTES secretion. B. canis replication was confirmed in infected placental explants and the infection elicited an increased secretion of TNF-α, IL-8, IL-6 and RANTES. This study shows that canine trophoblasts produce proinflammatory cytokines in response to B. canis infection and/or to stimulation with factors produced by infected monocytes and neutrophils. These cytokines may contribute to placental inflammation leading to abortion in B. canis-infected pregnant bitches.
Topics: Animals; Antigens, Bacterial; Brucella canis; Chemokines; Dogs; Female; Inflammation; Phagocytes; Placenta; Pregnancy; Toll-Like Receptors; Trophoblasts
PubMed: 29036184
DOI: 10.1371/journal.pone.0186561 -
Microbial Pathogenesis Feb 2020Brucella spp. are facultative intracellular pathogens and zoonotic agents which pose a huge threat to human health and animal husbandry. The B. melitensis, B. abortus,...
Deletion of the LuxR-type regulator VjbR in Brucella canis affects expression of type IV secretion system and bacterial virulence, and the mutant strain confers protection against Brucella canis challenge in mice.
Brucella spp. are facultative intracellular pathogens and zoonotic agents which pose a huge threat to human health and animal husbandry. The B. melitensis, B. abortus, and B. suis cause undulant fever and influenza-like symptoms in humans. However, the effects of B. canis have not been extensively studied. The quorum sensing-dependent transcriptional regulator VjbR influences the Brucella virulence in smooth type Brucella strains, such as B. melitensis, B. abortus and rough type Brucella ovis. However, the function of VjbR in the rough-type B. canis is unknown. In the present study, we discovered that deletion of this regulator significantly affected Brucella virulence in macrophage and mice infection models. The expression levels of virB operon and the ftcR gene were significantly altered in the vjbR mutant strain. We further investigated the protective effect of different doses of the vjbR mutant in mice and the results indicated that VjbR conferred protection against the virulent B. canis strain. This study presents the first evidence that the transcriptional regulator VjbR has important function in B. canis. In addition, according to its reduced virulence and the protective immunity it induces in mice, it can be a potential live attenuated vaccine against B. canis.
Topics: Animals; Bacterial Proteins; Bacterial Vaccines; Brucella canis; Brucellosis; Cell Line; Gene Deletion; Gene Expression Regulation, Bacterial; Host-Pathogen Interactions; Macrophages; Mice; Mutation; Quorum Sensing; RAW 264.7 Cells; Repressor Proteins; Trans-Activators; Type IV Secretion Systems; Virulence; Virulence Factors
PubMed: 31715318
DOI: 10.1016/j.micpath.2019.103865 -
Preventive Veterinary Medicine Jul 2019Canine brucellosis, caused by the bacterium Brucella canis, is a zoonotic and largely reproductive disease of dogs. The disease is a recognized problem in canine...
BACKGROUND
Canine brucellosis, caused by the bacterium Brucella canis, is a zoonotic and largely reproductive disease of dogs. The disease is a recognized problem in canine breeding populations, and the risk to individuals assisting with birthing is well described. Prior to 2015, all cases of canine brucellosis reported to the Minnesota Board of Animal Health were in dogs used for breeding. In 2015, canine brucellosis was identified in eight Minnesota rescue dogs, all originating from specific geographic areas in South Dakota. Our objective was to measure the seroprevalence of B. canis in stray and previously owned dogs entering a large Minnesota animal rescue organization to determine if our observations represented a localized or generalized disease issue among rescue dogs.
METHODS
A stratified random sample of stray and previously owned dogs entering the largest Minnesota animal rescue organization between November 1, 2016 and November 7, 2017, was tested for B. canis antibodies by the 2-Mercaptoethanol Rapid Slide Agglutination Test (2ME-RSAT) (Zoetis d-TEC CB kit). Sample sizes for each strata were calculated using previously published seroprevalence estimates. Blood from selected dogs was collected, serum harvested, and transported to the Minnesota Veterinary Diagnostic Laboratory for testing. Positive samples in the 2ME-RSAT were shipped to Cornell University for confirmation by Agarose Gel Immunodiffusion (AGID) testing. Demographics, state and setting of origin, and health status were collected on study-dogs.
RESULTS
Of the 10,654 dogs accepted by AHS during the study period, 943 (8.9%) were selected for testing. Most study dogs arrived from Oklahoma (28%), Alabama (18%), and Minnesota (12%). The median age of study dogs was 1.5 years; 303 (32%) were intact males and 294 (31%) were intact females. Most study dogs were strays (n = 716, 76%). Of the total, 22 (3.1%) stray and eight (3.5%) owner-surrendered dogs were presumptively positive by RSAT; one (0.11%) of the stray dogs was positive by 2ME-RSAT and confirmed by AGID. The positive dog was a healthy-appearing 1 year-old neutered male beagle from Texas.
CONCLUSIONS
The seroprevalence of canine brucellosis in dogs entering Minnesota for adoption from multiple states was low. Never-the-less, care must to be taken to consider all potential risks and outcomes of interstate and international dog trade, including the spread of infectious diseases such as canine brucellosis.
Topics: Animal Welfare; Animals; Antibodies, Bacterial; Brucella canis; Brucellosis; Dog Diseases; Dogs; Female; Male; Minnesota; Seroepidemiologic Studies
PubMed: 31097129
DOI: 10.1016/j.prevetmed.2019.04.015 -
Gene Apr 2022Brucella canis is responsible for canine brucellosis, a neglected zoonotic disease. The omp25 gene has been described as an important marker for Brucella intra-species...
Brucella canis is responsible for canine brucellosis, a neglected zoonotic disease. The omp25 gene has been described as an important marker for Brucella intra-species differentiation, in addition to the ability to interact with the host immune system. Therefore, this study investigated the omp25 sequence from B. canis strains associated to a phylogenetic characterization and the unveiling of the molecular structure. In vitro analyses comprised DNA extraction, PCR, and sequencing of omp25 from 19 B. canis strains. Moreover, in silico analyses were performed at nucleotide level for phylogenetic characterization and evolutionary history of B. canis omp25 gene; and in amino acid level including modeling, dynamics, and epitope prediction of B. canis Omp25 protein. Here, we identified a new mutation, L109P, which diverges the worldwide omp25 sequences in two large branches. Interestingly, this mutation appears to have epidemiology importance, based on a geographical distribution of B. canis strains. Structural and molecular dynamics analyses of Omp25 revealed that Omp25 does not sustain its native β-barrel. Likewise, the conformation of B-cell epitope on the mutated region was changed in Omp25 protein. Even without an evolutive marker, the new identified mutation appears to affect the basic function of B. canis Omp25 protein, which could indicate virulence adaptation for some B. canis strains in a context of geographical disposition.
Topics: Bacterial Proteins; Brucella canis; Evolution, Molecular; Genes, Bacterial; Models, Molecular; Mutation; Phylogeny; Polymerase Chain Reaction; Protein Conformation; Sequence Analysis, DNA
PubMed: 35031422
DOI: 10.1016/j.gene.2021.146175 -
Infection and Immunity Dec 2015Canine brucellosis caused by Brucella canis is a disease of dogs and a zoonotic risk. B. canis harbors most of the virulence determinants defined for the genus, but its...
Canine brucellosis caused by Brucella canis is a disease of dogs and a zoonotic risk. B. canis harbors most of the virulence determinants defined for the genus, but its pathogenic strategy remains unclear since it has not been demonstrated that this natural rough bacterium is an intracellular pathogen. Studies of B. canis outbreaks in kennel facilities indicated that infected dogs displaying clinical signs did not present hematological alterations. A virulent B. canis strain isolated from those outbreaks readily replicated in different organs of mice for a protracted period. However, the levels of tumor necrosis factor alpha, interleukin-6 (IL-6), and IL-12 in serum were close to background levels. Furthermore, B. canis induced lower levels of gamma interferon, less inflammation of the spleen, and a reduced number of granulomas in the liver in mice than did B. abortus. When the interaction of B. canis with cells was studied ex vivo, two patterns were observed, a predominant scattered cell-associated pattern of nonviable bacteria and an infrequent intracellular replicative pattern of viable bacteria in a perinuclear location. The second pattern, responsible for the increase in intracellular multiplication, was dependent on the type IV secretion system VirB and was seen only if the inoculum used for cell infections was in early exponential phase. Intracellular replicative B. canis followed an intracellular trafficking route undistinguishable from that of B. abortus. Although B. canis induces a lower proinflammatory response and has a stealthier replication cycle, it still displays the pathogenic properties of the genus and the ability to persist in infected organs based on the ability to multiply intracellularly.
Topics: Animals; Bone Marrow; Brucella abortus; Brucella canis; Brucellosis; Dogs; Female; Gene Expression; Interferon-gamma; Interleukin-12; Interleukin-6; Liver; Lymph Nodes; Male; Mice; Mice, Inbred BALB C; Species Specificity; Spleen; Tumor Necrosis Factor-alpha; Type IV Secretion Systems
PubMed: 26438796
DOI: 10.1128/IAI.00995-15